248 Analytical Notices of Books. 



The new genus Xiphosoma is divided from the true Bo«, being 

 intended to comprise those species which are not furnished with a 

 hook on each side the anus. It is also distinguished by its very 

 compressed body, and by its large teeth slightly curved back- 

 wards, three or four of which are crowded together in front on 

 each side of the jaws, resembling in form the fangs of the Vipers. 

 The habits of this genus are also diflferent from those of the Bua^ 

 as the species live almost constantly in the water or on aquatic 

 shrubs ; nor do they ever attain the immense size of those dread- 

 ful serpents. 



The genus Ophts, belonging to the Viperine family, forms a 

 transition from the innocuous to the poisonous serpents ; closely 

 resembling the former in appearance, but distinguished from them 

 by a fang on each side of the upper jaw, between which is a series 

 of small imperforate teeth. The single species is named Ophis 

 Merremii: it feeds on toads, and the figure given of it whimsically 

 enough represents it in the act of swallowing one, the hinder feet 

 of which projecting from the mouth give it a singular appearance, 

 and might at first view be mistaken for a part of the serpent 

 itself. 



MicruruSy a new genus forming part of the section Ilydrini, has 

 a very great analogy to Elaps, but is venomous. Its characters are 

 ** Tail very short, rather acute at the apex ; scuta of the tail be- 

 neath partly entire and partly divided ; head indistinct, obtuse, 

 with nine scuta above." 



The remaining genus established by M. Wagler, Leposternon, 

 is extremely interesting as presenting a connecting or osculant 

 group between the two grand divisions of Reptiles proposed by 

 Merrem, the Pholidota and the Bntrachia. In every respect it 

 coincides with the serpentine group of the latter, except in its 

 sternum being covered with scuta, a structure which closely con- 

 nects it with the true serpents included in the former section. 

 The only species, Leposiernon microcephalum, is described after 

 a single specimen found in the neighbourhood of Rio de Janeiro. 

 Its appearance and habits are very similar to those of the yim- 

 phisbcBtice. 



