60 



fibres, of a siil)-in\ieosa lyino- internal to tliese, and of a 

 nuu'osa which is a sinijile eolnnuiar or enl)ieal epithelium 

 eontaining' o-oblet eells. Four pyloric ctBca (Cce. fig". '-21) 

 are present. Day (" l^ritish Fishes," vol. II., p. 26) states 

 thai only 1\vo are present, and Kyle ap[)arently also agrees 

 with this, ^^'hen the intestine is distended with food 

 these ca^ca may he ohscnred, hnt their presence may 

 always he delermiiied, and in Ihe yonng' fish (of 2 to 4 

 inches long) they aie nsmdly ])aiticnhii1y noticeable. One 

 is ])resent on tlu^ dorsal and proximal extremity of the 

 duodenum, two on the v(Mitial and proximal extremity, 

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

 larg-e fishes) frcun the ])ylorus. This last csecum may be 

 the larg-est of the four. They have a wide himen freely 

 communicating with that of the duodenum; their wall is 

 very similar in striicture except that the muscle layers 

 may not be so distinct. 



Tlie Pyloric Caeca are only seen in Teleostomatous 

 fishes. The number present is very variable, none being- 

 found in the S(»le and 191 having- been counted in Scomber. 

 There has l)een much discussion as to their morphology 

 and function. At one time they were leg-arded as the 

 homologues of the pancreas — ^an organ wliicli was then 

 supposed to be absent in Teleostomi. They iiave been 

 regarded as absoiptive organs and as accessory digestive 

 glands. Mordecai from observations on CI u pea sn p id?. '<.'</ ma 

 supposed that they served to store up reserve food material. 

 In the fishes ascending i Iamms to spawn, when piesumably 

 no food was l)eing takcMi, Ihe c;eca were found (hstended 

 with a brownish mucus-like substance which was absent 

 at other times in the year. Jildinger supposed them to 

 exercise an al>sorptive function. AViedersheim also held 

 this opinion, and correlated their presence with the 

 absence of a spiral valve (a device for increasing the 



