402 PEOr. G. B, HOWES ON THE 



was represented by tlie tumid and inpushed base of the ileum, 

 and from that it would appear to he, in all probability, derived. 

 A line drawn vertically through the same (a— /3 of fig. 17, PI. II.) 

 passes behind an overhanging lobe of the large intestine — the 

 CEecum {dv). Curiously enough no such enlargement was to be 

 seen in the second specimen ; and the question naturally arises 

 whether, after all, the differences between it and the other one 

 may not have been due either to over-distension in the one case 

 or over-contraction in the other. Purther investigation can 

 alone settle this matter; but it is interesting to point out that a 

 precisely similar diflE.culty arises in relation to the alleged dis- 

 covery, by Perrault *, of a caecum in Salamandra. 



Box vulgaris'^. Cuvier and Valenciennes state of the in- 

 testine of this fish (5. p. 354) " arrive dans la partie moyenne du 

 ventre, il se dilate subitement et donne meme une sorte du petit 

 cgecum tres-court a I'origine du rectum, qui se retrecit bientot et 

 se rend a I'anus." This " caecum " is, in this fish, unmistakable 

 and well marked externally, and it lies to the left side {dv , fig. 16). 

 The stomach of this species is remarkable for the characters of 

 its pyloric sac ; that {sf, fig. 17) instead of being short and 

 swollen, as is so generally the case among the Teleostei, is 

 elongated and tubular. The cardiac gastric sac {st'.) is con- 

 stricted at its middle and, with the base of the stomach, prolonged 

 back into a crescentric diverticulum, into the concave border 

 of which the head of the large intestine {id.) is received. On dis- 

 section of this fish from the side, the air-bladder is seen to be 

 greatly enlarged ; its posterior moiety tapers off" much less sud- 

 denly than usual, and it, together with the greatly developed fat 

 masses, obliterates for the most part the posterior two thirds of 

 the ccelom. The caecum, when examined with sufficient care, is 

 seen to be situated dorso-laterally rather than laterally, and to 

 occupy a position which points very strongly to the conclusion 

 that it and the immediately related intestinal wall have 

 undergone a displacement (in mutual adaptation to the sur- 

 rounding organs) of a precisely similar nature to that affecting 



* ' Mem. pour seryir a I'hist. nat. des Animaux,' 2," partie, pi. 16, p. 481. 

 {Cf. Milne-Edwards, Le90ns s. 1. Pliys. et I'Anat. Comp. t. vi. p. 354.) 



t I have to thank Dr. Giinther, F.E.S., for a well-preserved specimen of 

 this fish. 



Cuvier and Valenciennes describe (5. p. -364) two cseca in B. salpa. I regret 

 having been unable to procure an individual of this species. 



