58 ME. T. J. PAEKER ON THE INTESTINAL 



ture which must offer an immense amount of resistance to the passage of the intestinal 

 contents, and, of course, making a decidedly greater proportional increase of surface 

 than in any of the cases recorded of the Eay. The difficulty of cleaning out the intes- 

 tine afforded a good criterion of the forms of these points ; the finely divided contents 

 stuck so tightly between the successive " cones," that a stream of water was often quite 

 insufficient to dislodge them. In fact the chyle (if one may apply the term to what 

 rather resembled fine mud) completely filled up the whole available space in tlie intes- 

 tine, so that, although the animal was preserved entire in spirit, the gut and its valve 

 were iu as good a condition for examination as if the former had been carefully emptied 

 and distended with spirit while fresh. The pyloric valve was very perfect, having the 

 form of a short conical tube projecting into the bursa entiana, with a very small aper- 

 ture at its apex. This, of course, brought about the result referred to, that only finely 

 divided matter could find its way into the intestine. 



Another point I may mention about this specimen is the great thickness of its walls 

 at the posterior end ; the thickness was actually greater than the diameter of the 

 lumen at that part. This may have been a mere individual abnormality ; but it seems 

 not impossible that this increase of muscular substance had relation to the great force 

 necessary to drive on the contents in a gut with so peculiar a spiral valve. 



In a smaller specimen of the same species there were eight turns to the valve, of 

 which the first five had a forward, the last three a backward direction ; so that the 

 valve was intermediate in character between C and D. 



§ 15. In Notidanus I found the valve to have twenty turns, and to be very much 

 what fig. 1, PI. X., would be if its posterior turns reached the centre — that is, inter- 

 mediate between B and C, and approaching more nearly to the former. The pylorus 

 is like that of Scyllium, projecting into the cavity of the intestine as a short tube with 

 a narrow aperture, and forming a highly perfect valve. 



§ 16, In Cestracion pkilippi there were eight turns to the valve i; these, again, were 

 intermediate between B and C, but approached more nearly to the latter type than in 

 Notidamis. The pylorus was remarkable, being very wide and quite devoid of any well- 

 marked valvular arrangement. In con-espondence with this, entire Cephalopods, par- 

 tially digested, were found in the intestine. 



§ 17. In Chimcera monstrosa (PI. XI. fig. 6) I found a valve of only three and a 

 half turns, remarkable from the fact that the attached edge did not form a regular 

 spiral, but for a part of its course (namely, during the first turn) formed a slightly 

 sinuous antero-posterior line. In consequence of this, the second compartment of the 

 intestine was fully half as long again as the bursa entiana. 



§ 18. The only other Elasmobranchs which I have been able to examine are Zygcena 

 malleus and Carcharias lumensis, two of the genera which, instead of a spiral valve, 



' Dumeril (' Ichthyologie generale ') found the same number in this species. 



