Being Tranmctiom of the S. Afr. Phil. Society. Vol. XVII. 15 



Systema nervosum ut in Aplysiis propriis. Radula (linguae) 

 dentibus medianis elongatis, dentibus lateralibus numerosis non 

 denticulatis. — Glandula herniapbrodisiaca bepati non connata. 



This animal, with its peculiai' form, was tirst noticed by Rumph 

 (D'Amboin. Rariteitkammer, 2 ed., 1741, N. x., N. 5), who figured 

 the animal as well as its shell, but without any description. On the 

 figure of the shell, given by Rumph, Lamai'ck established the 

 genus Dolabella, whicli was adopted by Cuvier and afterwards by 

 malacologists. 



The form of the animal is quite peculiar, differing from that of all 

 other Aplysiidae ; it is posteriorly broader, and terminates in a 

 roundish oblique large disk, to the middle of which the rather 

 narrow, longish branchial slit is continued. The somewhat dolabri- 

 form shell well calcified, with thickened left margin ; the hinder part 

 narrower, its right margin is notched ; the hind end thicker, bent 

 downwards and to the right, with a sharp, prominent keel. 



The central nervous system as in the Aplysiae proper. 



The rasp (of the tongue) has longish median plate and long series 

 of undenticulated lateral plates. 



The hermaphrodite gland not coalescent with the liver. 



The genus seems confined to the Red Sea, the Indian and Pacific 

 Oceans. 



As the form called by Cuvier Dolabella Einnphii cannot now be 

 determined, this name must be reserved for the form figured by 

 Rang. This author has, moreover, drawn up a small series of 

 species (Z). Hasseltii, Teremidi, ecaudata-'- (truncata), and still others 

 have been named by Ehrenberg, Qouy and Gaimard, Sowerby, 

 Stearns {D. Hemprichii, tongana, elongata, californica f ) ; some of 

 them are merely established on the shell, which is rather variable in 

 form, and some are very likely merely varieties of a very widely 

 distributed species. 



DoL. RuMPHii, (Cuv.) Rang, var. 



{D. Bumphii, Cuv., I.e., p. 437, pi. xxix., fig. 1.) 

 D. Burnphii, Rang, I.e., p. 46, pi. 1. 



Aplysia tongana, Q. et G., Voy. de V Astrolabe, ii., 1832, p. 305, 

 pi. 23, figs. 6-7. 



* V. d. Decken, " Reisen in Ostafrica," iii., 1869; v. Martens, " IMollusken," 

 p. 65 : Dolabella ecauda, Rang (Zanzibar). 



t Tryon and Pilsbry, " Man. of Conchology," xvi., 1895-96, pp. 151-160. 



