322 Mr. Bell on Leptophina. 



bly nearer to the posterior than to the anterior margin : the lower 



valve is flat, its vertex placed near the center, and its margin 

 very thiu and reflected. The sinus through which the byssus 

 passes, is large and elongated, and placed in a cavity posterior to 

 the vertex of the lower valve. All the specimens I have seen 

 are preserved in argillaceous iron stone nodules. 



Art. XXXIX. On Leptophina, a group of Serpents 

 comprising the Genus Drt/inus of Merrem, and a newly 

 formed Genus proposed to be named Leptophis. By 

 Thomas Bell, Esq. F.L.S. 



The genus Coluber of Linnajus consists of several very dis- 

 tinct subordinate groups, some of which are so obvious as to 

 require merely a cursory observation to detect them, whilst others 

 demand a more rigorous investigation to discover their affinities, 

 and to assign their natural limits. The separation of the genus 

 Elaps by Schneider, of Naia and of Dipsas by Laurenti, of 

 Vipera by Daudin, of Dryinus by Merrem, &c. still leaves much 

 to be done before the groups are well understood, and their 

 natural arrangement ascertained. Of those which have hitherto 

 been established, not one rests on a firmer basis, or is more natu- 

 rally and distinctly defined than the genus Dryinus of Merrem : 

 but upon an examination of several other species of Linnean 

 Colubri, of similar habits and conformation, I find so many points 

 of affinity as to claim for them a situation in the same superior 

 group, though undoubtedly they must be considered as generically 

 distinct ; and to these I propose to give the name Leptophis 

 (from MiTTos gracilis and o(pis serpens). 



The whole of the serpents composing these genera live in 

 woods, entwining themselves amongst the branches of trees, and 

 gliding with great rapidity and elegance from one to another. 

 These habits, combined with the graceful slenderness of their 

 form, the beautiful metallic reflection from the surface in some 

 species, and the bright and changeable hues in others, place 

 them amongst the most interesting of the serpent tribe. Their 

 food consists of large insects, young birds, &c. which the extra- 



