TESTACEA. 29 



July, they produced eight spots of spawn between the 6th and 15th of 

 August. If equally prolific, four belonged to each. 



These spots contained from five to eight embryos. Figs. 8 and 9 

 are represented to be of the natural size ; fig. 10 natural size ; fig. 11, the 

 same, more enlarged ; fig. 12, spot natural size ; fig. 13, the same, en- 

 larged. 



The spot, figs. 10, 11, was produced on August 6, and two of the 

 young quitted it on the 24th. Thus attaining maturity in eighteen 

 days. One of those, contained in the spot, figs. 12, 13, which had been 

 deposited on August 14, attained maturity on September 6, being twenty- 

 three days. 



The figure of the nascent animal is less definite than that of adults. 

 There is still a greater difference in the shell. The shell of one while 

 included in the spawn, seemed to be fluted. Nor was this an illusion ; 

 it proved, in fact, to be so. But the fluting is probably obliterated with 

 age. The shell of the nascent animal just specified of figs, 12, 13, 

 though not a quarter of a line in diameter, was sulcated from the apex 

 down to the mai'gin, fig. 14. The same was equally conspicuous on the 

 internal surfiice, which may be elucidated from the inside of another 

 specimen as enlarged, fig. 15, and more highly enlarged, fig. 16. 



Perhaps the whole spot of spawn may be itself compared to a capsule 

 containing the individual ova, which seemed to be of a faint yellow 

 colour. 



The animal certainly renovates lost parts of the shell, where the 

 losses are not destructive of the tenant, as was proved under favourable 

 circumstances. A more distinct view of the contents will then gratify 

 the beholder. Thus, the upper surface of the anterior of an animal sur- 

 viving privation of half the shell appeared reddish, and a distinct view 

 was afforded of the position of the eyes. — Fig. 17, enlarged. 



These creatures seem constantly employing the mouth to besmear 

 the neighbouring surface of the substances whereon they rest. They feed 

 readily in confinement ; propagate also ; and they survive during a con- 

 siderable period. 



If contained in a sm.all-necked or any other phial, and so are iuac- 



