TIIK NAUTILUS. 127 



end rostrate and pointed ; truncated area impressed, its borders not 

 carinated and ill defined, rostrum faintly grooved, the rest of the 

 shell polished, with obsolete impressed lines ; inner margin denticu- 

 late ; hinge teeth well developed, laterals strong and near the cardi- 

 nals ; pallial sinus rounded and extending a little in front of the 

 beaks ; the latter are well-defined, not prominent and nearly central. 

 Lon. of shell 17, Alt. 8*9, diam. G mm. 



MOLLUSKS AS CAT-FISH FOOD. 



BY CHAS. C. ADAMS, 806 EMPIRE ST., BLOOMINGTON, ILL. 



In the Nautilus for Dec, 1891, Dr. AV. S. Strode spoke of the 

 destruction of Anodonta which some thought was the work of cat- 

 fish. 



Speaking of the food of the cat-fish, Ictcelurus nebtdoms, L. S. in 

 Vol. II, p. 461, Bull. 111., St. Lab. Nat. Hist., he says: "Mollusca 

 make one-fifth of the entire amount of the food — more than one 

 half of them Sphserium. This genus made nearly all the food of a 

 large group taken from the Illinois River at Pekin in September, 

 1882, and also of two other specimens taken in the Illinois River at 

 Peoria in Oct., 1887. Univalves were rarely present, amounting to 

 only two per cent, of the food, taken, however by eight of the spec- 

 imens. These included the usual forms — Valvata, Melantlio, and 

 Amnicola, taken with two or three specimens of Phijsa. Examples of 

 Pisidium were rarely noted, and two had eaten Unios." 



Speaking oi Ictcelurus punctatus, Raf., p. 456, he says ; " Molluscan 

 food was a decidedly important element, being found in fifteen of 

 the fishes and amounting to fifteen per cent, of the whole. Several 

 specimens had taken little or nothing else — notably six secured at 

 Havana in Sept., 1887, and one at Peoria in Oct., of the same year. 

 The Mollusca were about equally divided between gasteropods and 

 lamellibranchs, the former largely Melantho and Vivipara, 

 the latter usually Unio or Anodonta." 



" Notwithstanding the number of bivalves eaten by these fishes, 

 no fragment of a shell was ever found in their stomachs, but the 

 bodies of the animals had invariably been torn from the shell while 

 yet living as shown both by the fresh condition of the recently 

 indigested specimen and likewise by the fact that the adductor 



