210 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



fibres, of a sub-mucosa lying internal to these, and of a 

 mucosa which is a simple columnar or cubical epithelium 

 containing goblet cells. Four pyloric caeca (Cce. fig. 21) 

 are present. Day (" British Fishes," vol. II. , p. 26) states 

 that only two are present* and Kyle apparently also agrees 

 with this. When the intestine is distended with food 

 these caeca may be obscured, but their presence may 

 always be determined, and in the young fish (of 2 to 4 

 inches long) they are usually particularly noticeable. One 

 is present on the dorsal and proximal extremity of the 

 duodenum, two on the ventral and proximal extremity, 

 and one on the mid-ventral line about an inch distant (in 

 large fishes) from the pylorus. This last caecum may be 

 the largest of the four. They have a wide lumen freely 

 communicating with that of the duodenum ; their wall is 

 very similar in structure except that the muscle layers 

 may not be so distinct. 



The Pyloric Caeca are only seen in Teleostomatous 

 fishes. The number present is very variable, none being 

 found in the Sole and 191 having been counted in Scomber. 

 There has been much discussion as to their morphology 

 and function. At one time they were regarded as the 

 homologues of the pancreas — an organ which was then 

 supposed to be absent in Teleostomi. They have been 

 regarded as absorptive organs and as accessory digestive 

 glands. Mordecai from observations on Cfupea sapidissima 

 supposed that they served to store up reserve food material. 

 In the fishes ascending rivers to spawn, when presumably 

 no food was being taken, the caeca were found distended 

 with a brownish mucus-like substance which was absent 

 at other times in the year. Edinger supposed them to 

 exercise an absorptive function. AViedersheim also held 

 this opinion, and correlated their presence with the 

 absence of a spiral valve (a device for increasing the 



