OCCASIONALLY ZOOPHAGOUS. 335 



This must of necessity be the case with those which swim in 

 the open sea, and with those which live amidst the plant-like 

 corallines and florulent zoophytes, embracing the majority 

 of the Tritoniadae and Eolidae ; for, at the depths in which 

 these animated productions are found, no sea-weeds can 

 grow. * Thus Mr. Bennet tells us that the Glaucus feeds 

 greedily on the gelatinous Porpitae and Velellse ;*j- and in 

 the fleshy gizzard of the toothless and tongueless Tethys, 

 Cuvier found fragments of shells, and the legs and other 

 remains of little crabs.J I took what appeared to be the 

 fry (Fig. 68) of Asterias papposa from the stomach of a 

 Tritonia; and Sir John Graham Dalyell assures us that 

 the appropriate food of Tritonia hombergii is the Lobularia 

 digitata, a common and nauseous zoophyte. Messrs. Alder 

 and Hancock have seen the Eolis punctata devour other 

 Nudibranches, and make a repast of its own spawn ; and 

 Eolis coronata, with equal carnivorous propensities, does 

 not hesitate to feed on its own species, the weaker falling 



Fig. 68. 



Fig. 68, a, the upper, i, the under surface. 



a sacrifice to the cravings of the stronger. "Large indi- 

 viduals will content themselves with plucking off each 

 other's papillae ; but, should a smaller specimen be within 

 reach, it is most mercilessly attacked, the more powerful 

 animal laying hold of any part of the weaker that may hap- 

 pen to be nearest. The tail, however, is generally first 

 seized, and fierce and determined is the onset. The de- 



* Many testaceous Gasteropoda, which we conclude to be herbivorous 

 from the character of the shell, live at depths where sea-weeds are very 

 rare or awanting. These species may be presumed to live on corallines. 

 " Now that the observations of M. Decaisne, M. Kutzing and others have 

 so clearly proved the vegetable nature of that singular production (the Nul- 

 lipore), so long regarded as a zoophyte, the source of the food of the holos- 

 tomatous testacea in these deep regions is no longer problematical." 

 E. FORBES in Reports Brit. Assoc. 1843, p. 165. 



t Proc. Zool. Soc. 1836, iv. 116 and 119. Mem. p. 12. 



Rare and Rem. Anim. Scot. ii. 180. 



