APLYSIID^E. 63 



PL 62, figs. 1, 2, represent Aclesia pleii ; fig. 3, is a diagrammatic 

 figure representing the internal structure of the annexed genital 

 mass of Aplysia. 



Literature of the Aplysiidce. 



(I) After the early work of BOHADSCH on the anatomy, and 

 LINNE on the " system," of Aplysia, the group received little atten- 

 tion until (II) CUVIER published his Memoire sur le genre Aplysia 

 in 1803. This was followed by an anatomical and systematic mon- 

 ograph of the Mediterranean forms by DELLE CHIAJE (1823), and 

 an illustrated monograph by BLAI^VILLE in Journal de Physique, 

 etc., Vol. 96, 1823. This monograph is the only systematic work 

 on the group which the writer has not seen. Its substance seems to 

 be repeated by Blainville in his articles, " Lievre marin " and 

 " Dolabelle," in the Dictionnaire des Sciences Naturelles, 1819, 

 1823. See also his Manuel de Malacologie, 1825. 



The next stage (III) in the history of the group is represented 

 by HANG'S monographic Histoire Naturelle des Aplysiens, 1825 ; one 

 of the most satisfactory monographs ever written on a mollusk 

 group, and, although now nearly seventy years old, still singularly 

 useful and complete. Scarcely any descriptions of species by more 

 recent writers approach those of Rang in lucidity and comprehen- 

 siveness. All of the main genera were understood by Rang, 

 although he considered them subdivisions only of Aplysia, using 

 that generic term in a rather wider than Lamarckiau sense. Sub- 

 sequent systematic work on the family has added little to Rang's 

 foundation aside from new species. The genera Aplysia, Dolabella 

 and Dolabrifera have been monographed by SOWERBY in the Conch- 

 ologia Iconica, but as the plan of that work excluded all but purely 

 shell features, these treatises are practically useless in the study of 

 the Aplysiidce, the shells of which are comparatively uncharacter- 

 istic. 



(IV) In quite recent times the Aplysiidce have attracted the at- 

 tention of numerous morphologico-systematic zoologists, among 

 whom may be mentioned BLOCHMANN, Mittheil. Zool. Sta. Neapel, 

 1884 ; VAYSSIERE, Recherches sur les Mollusques Opistob ranches, 

 1885 , MAZZARELLI, Atti della R. Accademia Scienze, etc., Napoli, 

 1890, 1891 ; Zool. Anz., 1889, etc. ; ZUCCARDI, Boll. Soc. Nat. 

 Napoli, 1890, and others. Nearly all of these investigations have 

 been made on Mediterranean forms. 



