September 13, 1831. 

 W. Yarrell, Esq. in the Chair. 



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

 of the Alligator Tortoise (Chelydra serpentina, Schweig.) were read 

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

 mach -j of the ilium and colon ; and of the cloaca, with the jpenis and 

 urinary bladders : a drawing of the latter was also exhibited j and 

 a drawing of the throat, representing the oesophagus and trachea in 

 their natural positions. 



" The animal was a male, and most probably young : its length 

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

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

 inches, and its breadth, following the curve, 1 foot 1 inch. 



" On theplastron being removed, and the scapulce (which are united 

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

 in a peritoneal sac, was exposed ; the scapula in their natural posi- 

 tion extending over it like an arch : next, and in the same cavity, 

 (for there was no division either by muscle or membrane,) the liver 

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

 pletely across from side to side : below the liver and occupying what 

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

 among which on the right side was 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 was the largest. The figure of the auricles was rounded, 

 each in magnitude equalled the ventricle : both auricles contained 

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

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

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

 chambers. 



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

 into two parts. On its inferior surface was 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, which passing under it fitted an elongated furrow 

 in the thick part of the lobe, and was closely united to il by the peri- 

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

 with the parietes of the carapace. The texture of the liver was 

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

 of dark green fluid, with which it was saturated. The gall duct en- 

 tered the duodenum 6 inches below the pylorus. The under surface 

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

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



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

 fully exposed. Beginning with the oesophagus, which immediately 

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

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



