432 



ANATOMY OF VERTEBRATES. 



in some Fishes : in others it is villous, with orifices of crypts at the 

 basal intervals of the flattened villi : in the Herring, fig. 290, the 

 surface is minutely honeycombed ; the cells or crypts being about 

 Y^-Q of an inch in diameter, and each is filled with a mass of 

 epithelial cells, as seen in the section B, fig. 290. The basis of 



290 



291 



Crypts of pyloric cseca, Herring, ccxxxi. 



Pancreas (/) of a Flounder, ccxxxn. 



the crypts is fibrous and projects between and often beyond the 

 level of their openings. The masses of epithelium resemble one 

 of the stages of the contents of the ultimate follicles of the 

 pancreatic acinus of a Mammal. The relation, however, of the 

 pyloric appendages of the Fish to that of the pancreatic gland of 

 the higher Vertebrates may be but one of analogy. 



There is a minute, but more constant glandular body present 

 both in fishes which possess {Salmo, Gadus, Perca) and those 

 that do not possess (Platessa, Belone, Brama, e.g.) the pyloric 

 creca. It is too small, fig. 2 9 l,f, for the performance of the pan- 

 creatic function in digestion ; but the contiguity of the terminal 

 dilatation of the duct, ib. g, with that of the ductus choledochus, 

 ib. e, and of their respective openings into the duodenum, suggests 

 that this glandule may be the rudimental homologue of the 

 pancreas of air-breathing Vertebrates. 



In the Lepidosiren the body imbedded between the muscular 

 and serous coats of the stomach, and referred to as probably 

 ' splenic ' incxLV. p. 271, sends its secretion by ducts converging 

 to one canal which opens beyond the pylorus, close to the orifice 

 of the hepatic duct. 1 



1 According to ccxxxni. p. 10. 



