BOYCOTT AND JACKSON: ANATOMY OF HELICELLA " HERIPENSIS. '' 165 



continuous, band of bright brick-red pigment mixed with the usual 

 black J in caperata this was reduced to one or two spots about the 

 centre, often microscopical in size, or was absent altogether. 



The " heripensis " shells were relatively flatter than the caperata, the 

 indices '^'^aiutudV"" ' being about 165 and 145 respectively. 



The variation in colour and markings of the two species was not 

 very great. 



^ In the '■'■heripensis'" the majority of the specimens were of a 

 brownish colour, sometimes quite pale, with radiating markings and 

 more or less interrupted bands above the periphery, and several finer 

 bands below. A few specimens, however, were of quite a unicolorous 

 brown all over and entirely without markings except in one or two 

 instances where there was a peripheral whitish band. This plain 

 colour variety appears to be the one referred to by Rev. C. E. Y. 

 Kendall as var. lutescens} 



In caperata the only noteworthy variation was the ornata form which 

 occurred very sparingly. 



A number of specimens of both forms was dissected. As regards 

 the alimentary system and the larger nerves and ganglia no difference 

 could be made out, except that (i) the jaw in ^'heripensis" was 

 stronger, darker and more markedly rugose, and (2) there appeared 

 to be rather fewer transverse rows in the radula in "heripensis." In 

 a series of caperata radula^ taken from shells of from 8'4 to 9*9 mm. 

 diam." (mean 9*2 mm. diam., 6'3 mm. alt.) the number of transverse 

 rows varied from 85 to 119, average 99; the parallel series of "heri- 

 pensis" ranged from S'l to ii'2 mm. (mean lo'i mm. diam., 62 mm. 

 alt.) and had from 87 to 94 transverse rows, average 91. The 

 difference is not large but becomes perhaps more significant from the 

 fact that in both caperata and "heripensis" the number of rows tends 

 to increase as the shell becomes larger. Hence we should have 

 expected the "heripensis" to have had rather more rows than the 

 caperata. The number of teeth in a transverse row varied from 47 to 55 

 (average 51) m caperata and from 51 to 61 (average 55) in "heri- 

 pensis.'' The total number of teeth was therefore in both forms just 

 about 5,000. The shape and size of the individual teeth were the 

 same in both series, and corresponded with Bowell's figure^ oi caperata. 

 The bifidity of the endocone on the marginal teeth to which Bowell 

 drew attention^ was, perhaps, more easily perceptible in "heripensis" 



1 Journal 0/ Conch., vol. 13, igi2, p. 345. 



2 It has, we think, now become clear that the radula must be described with reference to the 

 size of the shell from which it comes. 



3 Proc. Malac. Soc, vol. viii,, (1909), p> 384. 



4 Ibid, p. 379. 



