no 



SPECIAL CONVERGENCE 



the mullet ; and the presence of sand was noted 

 in the pyloric cceca. The latter arise in tufts 

 along the length of the duodenum (Fig. 10). 



Fig. io. Dissection of the alimentary tract of Chato'essus nasus 

 from the left side. The dotted line indicates the cut edge 

 of the body-wall. 

 i. Gall-bladder. 



2. Visceral nerve lying upon the cardiac tube of the stomach. 



3. Air-bladder. 



4. Ductus pneumaticus. 



5. Pyloric gizzard with a tuft of cceca projecting in front of it. 



6. Duodenum (green-tinted when fresh). 



7. Rectum. 



8. Hind-portion of left testis. 



9. Vas deferens. 



Here, then, we have two fishes belonging to 

 widely separated families, though pursuing similar 

 habits, and presenting independently an identical 

 modification of the pyloric division of the stomach. 

 I confess that at first acquaintance with this case 

 I began to distrust my own eyes ; perhaps it will 

 not strike the reader of these pages so forcibly ; 

 but I submit it as one of the most stringent 

 object lessons in homoplasy imaginable. 



It may be admitted that wherever there is a 



