30 L'mnean Society. [A])nl 2, 



The heart is situate below the oesophagus, in a strong pei-icardium ; 

 it consists of a single auricle and ventricle and a contorted bulbus 

 arteriosus, with a longitudinal valvular process as in the Siren. The 

 two branchial arteries, which wind round the gill-less arches, after- 

 wards unite together on each side, and give oif branches which form 

 the pulmonary arteries, or those which go to the air-bladders. 



The apparatus for aerial respiration commences by a short, single, 

 wide and membranous trachea, or ductus pneumaticvs, which com- 

 mences by a longitudinal laryngeal slit, one line in extent, situated 

 three lines behind the orifice of the pharynx : a single plate of car- 

 tilage is continued from this laryngeal opening forwards to that of 

 the pharynx : the plate is as broad as the floor of the pharynx, and 

 its office seems to be to prevent the collapse of the parietes of that 

 tube, and to keep a free passage for the air to the trachea. This tube 

 dilates at its lower end into a sac with very thin parietes, which com- 

 municates directly with each division or lobe of the air-bludder. 

 These lobes or lungs are partially subdivided into small lobes at their 

 anterior and broadest part ; and then continue simple and flattened, 

 gradually diminishing to an obtuse point situated behind the poste- 

 rior extremity of the cloaca. The whole of the parietes of the lungs 

 is honey-combed : the cells are largest, deepest and most vascular 

 and subdivided at the anterior and broader end of the lung. The 

 lungs are situated behind the ovaria, the ladneys, and the perito- 

 neum, which is in contact with merely that part of their ventral 

 flattened surfaces, not covered by other viscera. 



The two kidneys are quite distinct, very long and narrow, but 

 broadest towards the cloaca : the ureters communicate with the back 

 part of the common termination of the oviducts. There were not 

 any suprarenal bodies, nor any spleen. 



The ovaria are two long, flattened bodies, with ovisacs and ova of 

 diflFerent sizes : many between 2 and 3 lines in diameter, scattered 

 among clusters of other ova of smaller size. The oviducts are distinct 

 tortuous tubes, which commence by a veiy wide and thin-coated 

 portion, opening by a slit, 3 lines wide at their anterior extremity, 

 and not communicating with each other before opening into the pe- 

 ritoneal cavity, as in the Plagiostomes. The oviduct contracts and 

 performs many short undulations, adhering to the ovarian capsule 

 as it descends : its coats become thicker, and oblique spiral folds are 

 developed from the inner surface ; the capacity of the oviduct in- 

 creases before its termination, which is by a single prominent open- 

 ing, common to the two oviducts in the posterior part of the cloaca. 



A small Allantois is situated between the oviduct and rectum. 

 The cloaca receives the above parts in the following order,- — first, or 



