1()2 THE CANADIAN NATURALIST. [Yol. ix. 



furnished with three series of simihir teeth, as before stated. A 

 large tongue is present, and is free at its anterior extremity. 

 The suUet is thick and muscular, the stomach clouiiated, and 

 the intestine comparatively short, as in all carnivorous animals. 

 It has been said that its food consists of crustaceans, molluscs, 

 and fishes : but from my observations of the jMcnohirtnchiis in 

 an aquarium plentifully stocked with Molluscs, such as the Phy- 

 sadae, Limnaeans, PaludinEe, Planorbes, Anodonts, &c., as well 

 as Crustaceans, I am not warranted in asserting that it feeds on 

 anything other than true fishes. The liver is disproportionately 

 large ; a well-developed gall-bladder is present, as are also a 

 pancreas and spleen. The kidneys form two greatly elongated 

 organs, each like a cylinder rounded at both ends, and having a 

 w'ell- defined longitudinal depression — the hilum — throughout the 

 whole length of one side. 



The heart occupies but a limited portion of the thoracic cavity, 

 consisting of tw^o small auricles and a sliohtly laroer ventricle 

 which latter possesses, as it were, several minute secondary cavi- 

 ties, thus presenting the appearance more of a sponge-skeleton 

 than of one single chamber. The blood-corpuscles are oval, 

 nucleated, and of very great size, their long diameter being about 

 62 micro-millimetres. In connection with this it may be men- 

 tioned that the blood-corpuscles of man measure 7.5 micro-milli- 

 metres, or less than 3-^0^ of an inch in diameter ; in the frog they 

 are 22 mmm. in length ; and in amphiuma they are largest of 

 all, attaiuins: the extraordinary lenath of 77 micro-millimetres. 



True air-breathing lungs are present in the form of a pair 

 of much-elongated narrow sacs stretching back from the cavity of 

 the mouth, one on each side, and having the heart and oesophagus 

 lying between them. Each pulmonary sac is from two to three 

 inches long, and has a diameter nearly as great as that of an 

 ordinary goose-quill. The nostrils are in communication with 

 the pharynx. The nervous supply is by no means feeble, as is 

 evidenced by the great sensitiveness of the animal. 



An examination of the skeleton shows the inferior maxilla to 

 be formed of only two pieces or rami, which are directly articu- 

 lated with the skull, and the latter in its turn is jointed to the 

 first vertebra of the spine by two distinct and separate surfaces. 

 The vertebrae number thirty-three, are amphicoelous, and have 

 short, slender ribs attached to their transverse processes in the 

 dorsal and lumbar regions. The pectoral arch is in connection 



