130 Zoological Society. 



to form a median canal which passes from the basisphenoid to the 

 suture between that and the basioccipital, where it terminates in the 

 median canal continued to the orifice described by M. De Blainville 

 as the posterior nostril. The second passage leads from the floor of 

 the tympanic cavity to a short canal which bends towards its fellow, 

 expands into a sinus and divides : one branch descends and termi- 

 nates in the small lateral foramen at the lower end of the suture be- 

 tween the basioccipital and the basisphenoid : the other branch 

 continues the course inwards and downwards until it meets its fellow 

 at the median line of the basioccipital, and it forms the posterior 

 primary division of the common median canal : this soon joins the 

 anterior division, and the common canal termmates at the median 

 opening below. Membranous tubes are continued from the three 

 osseous ones, and converge to terminate finally in the single Eusta- 

 chian orifice on the soft palate behind the posterior nostril. The 

 mucous membrane of the palate lines the various osseous canals 

 above described, and is continued by them into the lining membrane 

 of the tympanum." 



With regard to the homologies of the above described air-passages, 

 the author states that the lateral canals answer to the simple Eusta- 

 chian tubes of Lizards and Mammals, and that the median canal, 

 with its dichotomous divisions, is a speciality peculiar to the Croco- 

 dilian reptiles. 



The memoir was illustrated by nine drawings of the size of nature. 



ZOOLOGICAL SOCIETY. 



July 24, 1849.— John Edward Gray, Esq., F.R.S., in the Chair. 

 The following papers were read : — 

 1. Notes on the Serpents of St. Lucia. By Lieut. Tyler, 

 R.E. Communicated by the Secretary. 



Of the snakes of the island of St. Lucia, the most numerous species 

 is the " Rat-tail ; " then follow the " Couresse," the " Clibro,^' and 

 the " Tete Chien ; " and in this order I propose to give you, as I 

 promised, a short description of each. 



1 . Craspedocephalus atrox, Gray. The Rat-tail Serpent. 



This much-dreaded serpent, which attains a length of from five to 

 six, and sometimes even seven feet, and a circumference of from four 

 to five inches, bears a strong resemblance, as to its shape and nature. 



