GASTEROPODES. 317 



the grains composing the spawn, and of snowy whiteness, had dissolved, 

 when numerous Nautilines swam as pure white specks amidst the water, 

 no larger than those from other species of the tribe. 



I have remarked on different occasions, indeed, that Nautilines from 

 the larger kinds were as small as Nautilines from the smaller ; and that 

 those of the E. papillosa exhibited the cylinders with the cilia almost as if 

 protruding from within, like wheels ; and, when withdrawn, that the 

 cylinders closed like conic frusta over them ; also, that the intestinal 

 organization consisted of at least seven distinct portions. 



On studying the external configuration of the Eolis papillosa, the 

 observer must beware of delusion, from the contraction attendant on 

 extenuation from spawning. 



PLATE XLV. 



FIG. 23. Eolis papillosa : back, before spawning. 



24. Belly. 



25. Another specimen : back, after spawning. 



26. Belly. 



27. Spawn. 



Note. Besides the preceding, which I conclude to be all distinct 

 species, various others have occurred, which, though less definitely cha- 

 racterised, are evidently allied to the same tribe. I shall select one as 

 an example, regretting that any obscurities disguised it. 



I. This may be descriptively called the Fan-head Eolis, as it cer- 

 tainly approaches more nearly to the race last under discussion than to 

 any other. 



Length three lines, breadth half a line. The anterior extremity 

 dilates into two flat leaves, capable of folding together. Towards the 

 side of each, a stout and rather short cylindrical tentacular organ rises 

 upright from the back of the neck ; and behind them are two very black 



