September 13, 18S1. 

 W. Yarrell, Esq, in the Chair. 



At the request of the Chairman the following notes of a dissection 

 of the Alligator Torioise {Chelydra serpentina, Schweig.) were read 

 by Mr. Martin. They were illustrated by preparations of the sto- 

 mach ; of the ilium and colon ; and of the cloaca, vvith ihe penis and 

 urinary bladders : a dravving of the latter was also exhibited ; and 

 a dravving of the throat, representing ihe cesophagus and trachea io 

 their natūrai positions. 



" The animal vvas a malė, and most probably young : its length 

 from the nose to the aiiits being 1 foot 11 inches, and from the anus 

 to the end of the tail 6 inches. The length of the carapace was 1 1-į- 

 inches, and its breadth, follovving the curve, ] foot 1 inch. 



" On the plastron being removed, and the scapulcB (which are united 

 to it by intervening museles) being turned back, the heart, inclosed 

 in a peritoneal sac, was exposed ; the scapulce in their natūrai posi- 

 tion extending over it likę an arch : next, and in the šame cavity, 

 (for there vvas no division either by musele or merabrane,) the liver 

 was seen, divided into two distinct portions, and stretching com- 

 pletely across from side to side : he\ow the liver and occupying vvhat 

 may be called the pelvic portion of the cavity, lay the intestines, 

 among which on the right side vvas seen the colon or commencement 

 of the large intestines enfolding the spleen. 



" The heart consisted of one ventricle and two auricles, the right 

 of which vvas the largest. The figure of the auricles vvas rounded, 

 each in magnitude eąualled the ventricle : both auricles contained 

 coagulated blood. The ventricle vvas in shape acuminate, of a red 

 colour, and firm and fleshy in structure. Its camece columnce were 

 Btrong, distinct, and numerous, but did not separate it into cells or 

 chambers. 



" The liver consisted of two lobes. The right lobe vvas divided 

 into two parts. On its inferior surface vvas situated the gall-bladder 

 buried in its substance and containing dull green bile : the duct 

 barely half an inch long. The edge of the left lobe of the liver co- 

 vered the stomach, vvhich passing under it fitted an elongated furrovv 

 in the thick part of the lobe, and vvas closely united to it by the peri- 

 toneum. The outer curvature of the stomach was placed in contact 

 vvith the parietės of the carapace. The texture of the liver was 

 soft and spongy, easily broken dovvn, and pouring out an abundance 

 of dark green fluid, vvith vvhich it vvas saturated. The gali duct en- 

 tered the duodenum 6 inches belovv the pi/lorus, The under surface 

 of the liver on the right side vvas connected to the duodenum, and 

 partially to the lung on the šame side, by peritoneal attachments. 



" On the liver being removed the course of the intestines vvas more 

 fully exposed, Beginning vvith the cesophagus, vvhich immediately 

 on proceeding from the pharynx beconies firm and- muscular (the 

 [No. XI.] ZuoL. Soc. Proceedings of the Comm. of Science. 



