CHITON. 207 



full size in proportion to the head. Loven justly re- 

 marks that, if we compare the development of Chiton 

 with that of other MoUusca, it is evident that the circle 

 of cirri, by means of which the animal moves in its first 

 or swimming stage, corresponds vrith the cirri of the 

 front lobe in the young of other Gasteropoda and of the 

 Acephala. Mr. Clark recorded some important remarks 

 on the reproduction of C. marginatus in the ^ Annals 

 and Magazine of Natural History^ for December 1855, 

 being the same year as that in which Loven^s were pub- 

 lished. One of several individuals, placed in a vessel 

 of sea- water on the 23rd July 1855, poured out for 

 several minutes a continuous stream of flaky-white \is- 

 cous matter, like a fleecy cloud, and then discharged 

 ova — not in volleys, but one or two at every second for at 

 least fifteen minutes, forming a batch of from 1300 to 

 1500 ; a thousand or more remained in the ovary, per- 

 haps not sufficiently matured for parturition. The fluid 

 and ova were emitted " from under the centre of 

 the coriaceous integument of the posterior terminal 

 valve,"*' in the same way as the author had described it 

 to take place from the posterior extremity of Denta- 

 lium. Each egg was enveloped in a pale yellow mem- 

 brane, and was of a somewhat globular shape, being a 

 little compressed or oblate at what may be termed the 

 axis ; it appeared to be about the 100th of an inch in 

 diameter. The ova were entangled in the tenacious 

 fluid which had been previously poured out — this being 

 seemingly a provision for preventing their being washed 

 away until the fry were prepared to emerge. In about 

 24 hours afterwards the fry became disengaged from 

 their common nidus, and swam about with great viva- 

 city in every direction, crossing a large breakfast saucer 

 in 30 or 40 seconds. They had by that time lost the 



