MONOTREMATA. 



Fig. 188. 



339 



Submaxillary glands. Echidna setosa (Original.) 



The pancreas is thicker in which the Monotremes again resemble the 



Marsupials. In the Ornithorhynehus the ante- 

 rior and right lobe is four inches long, the pos- 

 terior and left lobe two inches and a half; the 

 right lobe is bent upon itself. In the Echidna, 

 besides the two lobes which are continued for- 

 wards from the left side, there is a third shorter 

 descending appendage.* The lobes are thin and 

 moderately broad in both Monotremes, and in 

 structure, size, situation, and general figure, the 



lobe of the spleen.* 



in the Echidna, and enlarges considerably to- 

 wards the duodenum. 



The principal difference occurs in the place 

 of termination of the pancreatic duct, which, 

 in the Ornithoihynchus, joins the ductus chole- 

 dochus, but in the Echidna terminates sepa- 

 rately in the duodenum and nearer the pylorus 

 than does the ductus choledochus. 



The arrangement of the hepatic and pan- 



creatic ducts is thus conformable to the Mam- spleen conforms to the Mammalian type, al- 



malian type, and the Ornithorhynehus, in the 

 place of the junction of these ducts near the 

 commencement of the ductus choledochus, ma- 

 nifests its affinity to the Marsupials, as the 

 same structure occurs in the Dasyure. 



The spleen (Jig. 187, u, u) consists of two 



though this is exhibited under a more than usual 

 complication of external form. 



CIRCULATING SYSTEM. 



Hlood of the Ornithorhynehus. A Mammal 

 presenting such striking resemblances in cer- 



lobes bent upon each other at an acute angle, tain parts of its organization to the oviparous 



* Mcckel, loc. cit. p. 46. 



* Cuvier, 1. c. t. iv. p. 591. 



