452 THE OPISTHOBEANCHIATE 



opaque white specks so freely scattered over the rest of the back 

 are absent ; it is not caused by the emargination of the pleuropodium, 

 for it is situated anteriorly to the point of fusion, and can be seen to 

 be independent of it. It is not always present. 



Alder and Hancock's descriptions and figure of the radula of this 

 species are incorrect as regards the structure of the large inner side- 

 plates, iuasmuch as they do not take into account a rhomboidal and 

 thickened fold which invariably exists at the internal angle of each 

 of these tooth-plates, comparable with a triangular fold found on 

 the same tooth of Lamellidoris (cf. PI. XXVII, fig. 5, and Alder 

 and Hancock's figures of the radulse of Goniodoris nodosa and 

 Lamellidoris depressa). Bergh^ has given more accurate descrip- 

 tions of the teeth, but only figures the isolated plates. He gives the 

 number of denticles on the inner plates as 25 (22 — 25) in an indi- 

 vidual measuring 12 mm. in length and 4*5 in breadth, preserved 

 in alcohol. In a larger specimen (neai'ly 1 inch in length) I found 

 the denticles to vary in number from 24 to 27, while in an indi- 

 vidual only -^ inch in length the average number was 17. In the 

 latter specimen also the external side-plates show several regularly 

 repeated indentations of the edge (fig. 5, |3), while those of old 

 individuals are more oval in form, and have mere traces of these 

 indentations. My fig. j3 does not well represent them. 



Herdman^ and Clubb have found a " second smaller denticulated 

 ridge on the large lateral spines of the radula " in some of their 

 specimens. It would be interesting to know whether the occurrence 

 of this second ridge can be traced to any physiological cause or cor- 

 related with some other structural change. 



47. *GrONiODORis CASTANEA, A. and H. 



During the past year six more specimens of this species have been 

 found. Two were dredged in the Cattewater, Oct. 8th, 1889, one being 

 •^ inch, the other -^ inch in length. The latter specimen is figured 

 on PI. XXVII (fig. 1) ; the figure is accurate in every respect except 

 that the tuberculate character of the sides of the foot is not so clearly 

 apparent as it should be. The oral veil of this young individual 

 differed considerably from the form which has been described as 

 typical of the species, and showed a closer approximation to that 

 existing in Goniodoris nodosa. The oral veil of an adult G. castanea 

 is figured on PI. XXVII, fig. 2 ; its anterior edge exhibits a double 

 or sinuous curve on each side, but in this specimen the veil possessed 



1 Bergh, Die Qattung Goniodoris, Malakozoologische Blatter, Neue Folge, Bd. i, 

 1880, pp. 123, 124, aud pi. iv. 



* Herdmau and Clubb, Second Report on the Nudibranchiata, Proc. Liverp. Biol. Soc, 

 iii, p. 227. 



