31b Transactions. — Zoology. 



the tail, 2 mm. The height of the (retracted) rhinophore is 

 2 mm. ; length of tentacle, 1 mm. ; height of the gill, 3 mm. ; 

 diameter of the branchial star, 7 mm. 



[Colour.] The colour of the back is whitish or faintly yellow- 

 ish white ; the tubercles white ; the head and foot inclining to 

 yellowish ; the clubs of the rhinophore and the gill are chrome- 

 yellow. One individual had the under-surface of the mantle- 

 flap spotted with violet-grey. 



[Externals.] In consistency the animal is somewhat stiff. 

 The form as in other Archidorids. The back is covered pretty 

 closely with tubercles of dissimilar size, somewhat flattened on 

 the apex (at least in the case of the larger ones) : they attain a 

 height and diameter of about 05 mm. Similar tubercles are 

 also present at the edge of the rhinophore-pits and gill-aperture, 

 [p. 36] The club of the rhinophore bears about 20 folia? ; the 

 branchial aperture is transversely oval ; the gills number 5 or 6 ; 

 the cylindrical anal papilla is relatively high (1 mm.). The 

 under-surface of the mantle-flap is smooth ; the sides of the body 

 angular. The foot has a distinct groove at its anterior edge ; 

 the tail is short ; the tentacles are short, thick, with grooves on 

 the under-side. 



[Remarks (p. 37).] Whether this form belongs to the genus 

 Homoiodoris remains for the present undecided, since the most 

 essential character — the armature of the vagina — was not esta- 

 blished owing to the condition of preservation. If this armature 

 noted [in the text] belongs to the sperm-duct, either a new genus 

 will have to be formed, or it belongs to the genus Artach&a* 

 in which, however, no prostate is developed. The vestibular 

 glands and sac existing in the present species are absent from 

 Homoiodoris and from Artachcea. From the hitherto known 

 species of Homoiodoris, as well as of Artacho?a, this new form is, 

 however, specifically distinct, as is evident from the comparison 

 of the radula — the innermost as well as the outermost teeth 

 being quite unlike those of other species. 



Atagema, Gray [p. 39]. 



Gray, fig. iv., 1850, p. 104 ; Guide, i., 1857, p. 209. 



Form and internal structure as in an Archidorid. The back 

 carries a median keel. As was so frequently the case, Gray 

 erected a new genus (Atagema) on a drawing (by Quoy and 

 Gaimard) of an animal presenting a somewhat peculiar appear- 

 ance. 



The animal described below belongs to the Archidoridido? : 

 it lias the general body-form of the family, with granulated 



* See Bergh, "System d. Nudibraneh: Gasteropoda," 1892, p. 1093. 



