446 Mr. W. Clark on the Pfuenomena of the 



XXX VII. — On the Phenomena of the Reproduction of the 

 Chitons. By William Clark, Esq. 



To the Editors of the Annals of Natural History. 



Gentlemen, Norfolk Crescent, Bath, November 1855. 



The Chitons have long been a source of difficulty to naturalists 

 with respect to systematic position; the most distinguished 

 names, Cuvier, Blainville, Milne-Edwards, and Prof. Forbes, are 

 at variance on this point, which to the present time has not 

 received a satisfactory solution. Cuvier alone considers them 

 true Mollusca ; Blainville refers them to the Annelidan Articu- 

 lata y Forbes speaks doubtingly ; and Milne-Edwards admits that 

 they are Gasteropoda, but hesitates to acknowledge them Mol- 

 lusca. 



I trust the following observations, though not so complete as 

 I could wish, will throw some light on their reproductive statiis 

 and natural position. 



The present paper has originated in a suggestion of the late 

 Prof. Forbes and Mr. Hanley, who in their ^ British Mollusca,^ 

 vol. ii. p. 390, "trust that some active observer resident by the 

 coast will occupy himself with studying the development of the 

 Chitons, and endeavour to ascertain the form they assume in 

 their larval condition. Whoever does so will make an important 

 discovery, and do more towards fixing the true position of these 

 anomalous creatures than all cabinet examinations of them have 

 yet enabled us to effect." And I have stated in my late work 

 on the ' British Marine Testaceous Mollusca,' p. 248, " that I 

 propose, if practicable, to carry out this idea, though the at- 

 tempt will be attended with uncertainties which need not at 

 present be alluded to.'' 



Chiton cinereus, Linnseus. 



Chiton cinereus, Brit. Moll. vol. ii. p. 402. 

 Chiton marginatus, variorum. 



On the 23rd July 1855, I obtained several examples of the 

 above species fixed on small pebbles from their natural habitat ; 

 these were carefully removed into saucers of sea-water and 

 sedulously examined every hour for many following days. In 

 the afternoon of the day of capture my attention was suddenly 

 attracted by observing one of the animals in the act of dis- 

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

 for at least 15 minutes, forming a batch of 1300 to 1500; there 

 were a thousand or more that remained in the ovarium, perhaps 

 not sufficiently maturated for parturition ; they were pale yel- 



