MOIJ.USCA OF PLYMOUTH. 405 



marking is concerned — in the species A. dejnhms {= fasciata) of 

 their descriptions. 



Radula.— In 1876, 1877, and again in 1878, Mr. A. R. Hunt,^ of 

 Torquay, obtained a number of Aplysise in Torbay of various sizes, 

 some of which were of the ordinary English type, the species punctata 

 of Blochmann and Vayssiere, the largest of these having a radula with 

 fifteen completely formed lateral teeth on each side in a single 

 transverse row, while others were of very much larger size, and are 

 referable to the species depilans of the same naturalists, the small- 

 est having, according to Mr. Hunt, twenty-six completely formed 

 lateral teeth on each side of the median row. Mr. Hunt, however, 

 by examining a series of radulse of different sizes found that the 

 number of lateral teeth as well as the number of transverse rows 

 was dependent upon the age (size) of the individual, and arrived at 

 the conclusion that probably his large specimens were not specifically 

 distinct from the smaller ones, but were simply unusually large in- 

 dividuals of the common English species, A. punctata, Cuvier. 



I owe to Mr. M. F. Woodward, of South Kensington, my acquaint- 

 ance with Mr. Hunt's papers, which were published in a journal not 

 generally known to zoologists, and had escaped my notice. Mr. 

 Woodward had intended to re-investigate the matter himself, but 

 upon finding that I was engaged in an examination of the Plymouth 

 Aplysise very courteously referred me to Mr. Hunt's papers, and, 

 as I am pleased to acknowledge, helped me in various other 

 ways. 



As to growth of the radula in either Aplysia depilans ov punctata, 

 the comparatively recent papers of Blochmann and Vayssiere render 

 little assistance. Blochmann figures the radula and teeth of a single 

 average-sized specimen of each " species," and gives their respective 

 forraulse ; while Vayssiere remarks upon the variability in the dental 

 formulae of A. punctata, and describes the structure of the teeth of 

 an average specimen, but for A. depilans gives a similar description, 

 and regrets having obtained no young individuals (1. c, pp. 67, 61). 

 From Blochmann's account, again, I cannot gather that he has exa- 

 mined young specimens of this latter species, for he gives the size 

 of the animal as from 10 to 20 cm., and only mentions '' quite young 

 individuals" as being fossihle exceptions to the general rule as to 

 the markings of the species (1. c, p. 32). 



Is there a possibility that the young Ajjlysia depilans is no other 

 than Aplysia punctata ? 



On PI. XXVIII the structure of the central tooth and of three 



' Hunt, On some Large Aplysix taken in Torlay in 1875, Trans. Devonshire Assoc, 

 vol. ix, 1877, pp. 400 — 403 ; On the Growth of Aplysiee in Torbay, Trans. Devonshire 

 Assoc, X, 1878, pp. 611—617. 



