Chapter XII: Part III: (continued.) (3)

The genera of birds peculiar to this sub-region belong to the following families:--Turdidæ (2 genera); Troglodytidæ (1 gen.); Vireonidæ (1 gen.); Corvidæ (2 gen.); Ampelidæ (1 gen.); Tanagridæ (1 gen.); Fringillidæ (2 gen.); Icteridæ (1 gen.); Formicariidæ (2 gen.); Tyrannidæ (2 gen.); Cotingidæ (1 gen.); Momotidæ (1 gen.); Trogonidæ (1 gen.); Trochilidæ (14 gen.); Conuridæ (1 gen.); Cracidæ (2 gen.); Strigidæ (1 gen.); in all 37 genera of land-birds. The Neotropical families that do not extend into this sub-region are, Pteroptochidæ; the sub-family _Furnariinæ_ of the Dendrocolaptidæ; the sub-family _Conophaginæ_ of the Tyrannidæ; the sub-family _Rupicolinæ_ of the Cotingidæ; Phytotomidæ; Todidæ; Opisthocomidæ; Chionididæ; Thinocoridæ; Cariamidæ; Psophiidæ; Eurypygidæ; Palamedeidæ; and Struthionidæ. On the other hand Paridæ, Certhiidæ, Ampelidæ, and Phasianidæ, are northern families represented here, but which do not reach South America; and there are also several northern genera and species, of Turdidæ, Troglodytidæ, Mniotiltidæ, Vireonidæ, Fringillidæ, Corvidæ, Tetraonidæ, and Strigidæ, which are similarly restricted. Some of the most remarkable of the Neotropical genera only extend as far as Costa Rica and Veragua,--countries which possess a rich and remarkable fauna. Here only are found an umbrella bird, (_Cephalopterus glabricollis_); a bell bird (_Chasmorhynchus tricarunculatus_); and species of _Dacnis_ (Ceroebidæ), _Buthraupis_, _Eucometis_, _Tachyphonus_ (Tanagridæ), _Xiphorhynchus_ (Dendrocolaptidæ); _Hypocnemis_ (Formicariidæ); _Euscarthmus_ (Tyrannidæ); _Attila_ (Cotingidæ); _Piprites_ (Pipridæ); _Capito_, _Tetragonops_ (Megalæmidæ); _Selenidera_ (Rhamphastidæ); _Neomorphus_ {54}(Cuculidæ); _Monasa_ (Bucconidæ); many genera of Trochilidæ; and _Nothocercus_ (Tinamidæ); none of which extend further north. A considerable number of the peculiar genera noted above, are also found in this restricted area, which is probably one of the richest ornithological districts on the globe.

_Reptiles._--These are much less known than the preceding classes, but they afford several peculiar and interesting forms. Snakes are perhaps the least remarkable; yet there are recorded 4 peculiar genera of Calamariidæ, 1 of Colubridæ, 1 of Homalopsidæ, 3 of Dipsadidæ; while _Boa_ and _Elaps_ are in common with South America. Lizards are much more specially developed. _Chirotes_, one of the Amphisbænians, is confined to Mexico and the southern part of the Nearctic region; _Heloderma_ forming a peculiar family, Helodermidæ, is Mexican only; _Abronia_ and _Barissia_ (Zonuridæ) are also Mexican, as is _Siderolampus_ belonging to the Scincidæ, while _Blepharactitis_ (same family) inhabits Nicaragua; _Brachydactylus_, one of the geckoes, is from Costa Rica; while _Phymatolepis_, _Lamanctus_, _Corytheolus_, _Cachrix_, _Corythophanes_ and _Chamæleopsis_, all belonging to the Iguanidæ, are confined to various parts of the sub-region. In the same family we have also the Antillean, _Cyclura_, and the Nearctic _Phrynosoma_ and _Tropidolepis_, as well as the wide-spread American genus _Anolius_.

Among the tortoises, _Staurotypus_, allied to _Chelydra_, is found in Mexico and Guatemala; and another genus, _Claudius_, has been lately described from Mexico.

_Amphibia._--These are chiefly Batrachians; _Rhinophryna_ (forming a peculiar family) being confined to Mexico; _Triprion_, a genus of Hylidæ, inhabiting Yucatan, with _Leyla_ and _Strabomantis_ (Polypedatidæ) found only in Costa Rica and Veragua, are peculiar genera. The Salamandridæ, so abundant in the Nearctic region, are represented by a few species of _Amblystoma_ and _Spelerpes_.

_Fresh-water fish._--Since the British Museum catalogue was published, a valuable paper by Dr. Günther, in the Transactions of the Zoological Society for 1868, furnishes much additional information on the fishes of Central America. In that part of the region south of Mexico, 106 species of fresh-water fishes are {55}enumerated; and 17 of these are found in streams flowing into both the Atlantic and Pacific Oceans. On the whole, 11 families are represented among the fresh-water fish, and about 38 genera. Of these, 14 are specially Nearctic,--_Amiurus_ (Siluridæ); _Fundulus_ (Cyprinodontidæ); _Sclerognathus_ (Cyprinidæ); and _Lepidosteus_ (Ganoidei). A much larger number are Neotropical; and several Neotropical genera, as _Heros_ and _Poecilia_, are more largely developed here than in any other part of the region. There are also a considerable number of peculiar genera;--_Petenia_, _Theraps_, and _Neotrophus_ (Chromides); _Ælurichthys_ (Siluridæ); _Chalcinopsis_ (Characniidæ); _Characodon_, _Belonesox_, _Pseudoxiphophorus_, _Platypoecilus_, _Mollienesia_, and _Xiphophorus_ (Cyprinodontidæ). A few peculiar Antillean forms are also present; as _Agonostoma_ (Mugilidæ); _Gambusia_ and _Girardinuus_ (Cyprinodontidæ). The other families represented are Percidæ (1 genus); Pristopomatidæ (2 gen.); Gobiidæ (1 gen.); Clupeidæ (2 gen.); and Gymnotidæ (1 genus).

On the whole the fish-fauna is typically Neotropical, but with a small infusion of Nearctic forms. There are a considerable proportion of peculiar genera, and almost all the species are distinct from those of other countries. The predominant family is that of the Cyprinodontidæ, represented by 12 genera; and the genus _Heros_ (Chromidæ) has here its maximum development, containing between thirty and forty species. Dr. Günther considers that a number of sub-faunas can be distinguished, corresponding to some extent, with the islands into which the country would be divided by a subsidence of about 2,000 feet. The most important of these divisions is that separating Honduras from Costa Rica, and as it also divides a very marked ornithological fauna we have every reason to believe that such a division must have existed during the latter portion of the tertiary epoch. We shall find some farther evidence of this division in the next class.

_Insects._--The butterflies of various parts of Central America and Mexico, having been largely collected, offer us some valuable evidence as to the relations of this sub-region. Their general character is wholly Neotropical, about one half of the {56}South American genera being found here. There are also a few peculiar genera, as, _Drucina_ (Satyridæ); _Microtia_ (Nymphalidæ); _Eumæus_ (Lycænidæ); and _Eucheira_ (Pieridæ). _Clothilda_ (Nymphalidæ) is confined to this sub-region and the Antilles. The majority of the genera range over the whole sub-region from Panama to Mexico, but there are a considerable number, comprising many of the most characteristic South American forms, which do not pass north of Costa Rica or Nicaragua. Such are _Lycorea_, _Ituna_, _Thyridia_, _Callithomia_, _Oleria_ and _Ceratina_,--all characteristic South American groups of Danaidæ; _Pronophila_ and _Dynastor_ (Satyridæ); _Protogonius_, _Pycina_, _Prepona_, _Nica_, _Ectima_ and _Colænis_ (Nymphalidæ); _Eurybia_ and _Methonella_ (Nemeobiidæ); _Hades_, and _Panthemos_ (Erycinidæ).

_Coleoptera._--These present some interesting features, but owing to their vast number only a few of the more important families can be noticed.

Cicindelidæ.--The only specially Neotropical genera recorded as occurring in this sub-region, are _Ctenostoma_ and _Hiresia_, both reaching Mexico.

Carabidæ.--Several genera are peculiar. _Molobrus_ is found in all parts of the sub-region, while _Onychopterygia_, _Phymatocephalus_, and _Anisotarsus_ are Mexican only. There are about 20 South American genera, most of which extend to Mexico, and include such characteristic Neotropical forms as _Agra_, _Callida_, _Coptodera_, _Pachyteles_, _Ardistomus_, _Aspidoglossa_, _Stenocrepis_, and _Pelecium_.

Lucanidæ.--Of this important family there is, strange to say, not a single species recorded in Gemminger and Harold's catalogue up to 1868! It is almost impossible that they can be really absent; yet their place seems to he, to some extent, supplied by an unusual development of the allied Passalidæ, of which there are five South American and six peculiar genera.

Cetoniidæ.--All the larger South American genera extend to Mexico, which country possesses 3 peculiar forms, _Ischnoscelis_, _Psilocnemis_, and _Dialithus_; while _Trigonopeltastes_ is characteristic, having 4 Mexican, 1 Brazilian, and 1 North American species.

{57}Buprestidæ.--In this family there are no peculiar genera. All the large South American groups are absent, the only important and characteristic genus being _Stenogaster_.

Longicorns.--This important group is largely developed, the country being well adapted to them; and their distribution presents some features of interest.

In the Prionidæ there are 6 peculiar genera, the largest being _Holonotus_ with 3 species; two others, _Derotrachus_ and _Mallaspis_, are characteristic; 3 more are common to South America, and 1 to Cuba. The Cerambycidæ are much more numerous, and there are 24 peculiar genera, the most important being _Sphenothecus_, _Entomosterna_, and _Cyphosterna_; while _Crioprosopus_ and _Metaleptus_ are characteristic of the sub-region, although extending into South America; about 12 Neotropical genera extend to Mexico or Guatemala, while 12 more stop short, as far as yet known, at Nicaragua. Lamiidæ have a very similar distribution; 13 genera are peculiar, the most important being _Monilema_, _Hamatoderus_, and _Carneades_, while _Phæa_ and _Lagochirus_ are characteristic. About sixteen typical Neotropical genera extend to Mexico, and 15 more only reach Nicaragua, among which are such important genera as _Anisopus_, _Lepturgus_, and _Callia_.

The land-shells are not sufficiently known to furnish any corresponding results. They are however mostly of South American genera, and have comparatively little affinity for those of the Antilles.

_Relations of the Mexican sub-region to the North and South American Continents._--The sudden appearance of numerous South American forms of Edentata in temperate North America, in Post-Tertiary times, as narrated in