102 [June, 



Pachydactylus, and Onychocephalus, and Causus rhombeatus. The genera Uro- 

 mastyx and Stellio are found in Northern, but do not appear to exist in S. Africa. 

 The study of the geographical distribution of animals, and especially of reptiles, 

 presents many very remarkable facts. Some species appear to have a very 

 wide distribution, others a very local. The Cistudo Carolina, for example, is 

 found in almost every part of the United States, but Emys Muhlenbergii and 

 Testudo polyphemus have a very limited range, the one being known only in a 

 small portion of the Northern States and the other of the Southern. The spe- 

 cies of reptiles of the United States are entirely different from those of Europe, 

 but there are a number of genera common to both ; among these are Testudo, 

 -Emys, Coronella, Tropidonotus, Psammophis, Coluber, Rana, Bufo, Salamandra. 



The genera Crotalus, Trigonocephaly or Elaps, all of which exist in the United 

 States, are not found in Europe, but the venomous serpents are replaced by the 

 viper, of which there are several species none of which are found with us, the 

 serpent called viper in the U. States being a Heterodon, a very harmless animal. 

 The viper is common in England but does not exist in Ireland, neither does 

 the genus Bufo. Some genera are very limited in their distribution, being found 

 in certain localities and nowhere else. Thus Amphiuma and Siren are found 

 in the Southern States; Menopoma, in the West and South; Menobranchus, in 

 the Western waters of the United States; Phrynosoma in New Mexico and 

 Texas ; Anota, of which but two specimens have yet been discovered, and 

 Homalosaurus in the Desert of the Colorado; Holbrookia or Cophosaurus in Texas; 

 Platysaurus, in Southern Africa ; Hypochthoon in lllyria. 



The species on the East and West Coast of South America differ almost en- 

 tirely from each other. The genus Proctotretus, comprising numerous species, 

 is found only in Peru. Other genera have a much wider distribution, but are con- 

 fined to certain large portions of the globe. Thus the Boas exist for the most 

 part in South America, the Pythons in Africa. According to Schlegel, no spe- 

 cies of serpent is found in all parts of the world, the Tortrix not an exception, 

 not being known in the United States. Gerrhosaurus is found in California, there 

 being but one species known in that State, but there are six species of the same 

 genus in Mexico, and six others, all described by Dr. Smith, exist at the Cape 

 of Good Hope. 



My friend, Professor Baird, informs me that he has recently received, from 

 the We ? tern portion of the United States, a specimen of Dipsas, a genus of ser- 

 pents not hitherto known to inhabit the United States. The genera Chamaeleo, 

 Euprepis, Eremias, Cordylus, Gecko, Hemydactylus, Ptyodactylus, Stenodac- 

 tylus, Phyllodactylus, Acanthodactylus, Zonurns, Varanus, are entirely unknown 

 in the United States, nor are there any true Lacertae. Among fresh water tor- 

 toises, the Emydes of the United States are very numerous, Prof. Holbrook having 

 figured as many as seventeen species ; they occur., also, in great numbers in In- 

 dia, twelve species having been described by Dumeril and Bibron, in their great 

 work on Reptiles. It is very remarkable, however, that but one species of 

 Emys, the Emys spengleri, of which we have the shell only in the Academy, 

 has been described as existing in the whole continent of Africa, whereas the 

 tortoises in the Southern portion of that country are numerous. Two species 

 of Sternothaerus are described as belonging to the island of Madagascar, the 

 niger and nigricans. We have the shell of one from Western Africa, which 

 probably belongs to the latter species. Among serpents the genus Tropidonotus 

 has a very wide range, being found more or less abundantly in almost every part 

 of the globe except Africa and Australia. The genus Trigonocephalus is not found 

 in Africa, but the vipers in that quarter of the globe are numerous, no less than 

 six species being described by Dr. Smith as inhabiting S. Africa, viz.: Echidna 

 arietans, atropos, atropoides, inornata, and Cerastes cornulus and ocellatus. To 

 these may be added the Vipera nasicofnis, or Natter Jack, which is found both 

 in Southern and Western Africa. Among the most remarkable of serpents are 

 those comprised in the genus Hydrophis. They are sea serpents, and <k inhabit 

 exclusively the inter-tropical latitudes of the Indian seas and of the great Pa- 

 cific Ocean." 



It has been a matter of doubt whether these animals are poisonous or not; but 



