Messrs. Alder and Hancock on the genus Eolidina. 125 



several new Bulbuls ; and of Kectariniidce, Arachnothtra inornata, 

 Nect. goolpariensis, Phayrei (vel Hasseltii r), mahrattensis, juyularis, 

 lepida (v. javunica), and phoenicotis, Diceum cruentatum, cuntillans, 

 and chrysochlorum, nobis, &c. &c. A shikaree in ray employ has just 

 come in with three specimens of Phoenicophaus tristis, a live young 

 Nisaetus caligatus, &c. 



XYII. — Remarks on the genus Eolidina of M. de Quatrefages. 

 By Joshua Alder and Albany Hancock, Esqrs. 



In a former communication on the Nudibranchiate !Mollusca, we 

 took occasion to express an opinion that the genus Eolidina of 

 M. de Quatrefages was not a good one, the species on which it 

 was founded being, in our opinion, nothing more than an Eolis 

 imperfectly observed. It was irrelevant to the object of our former 

 paper to enter into detail on the reasons which induced us to 

 form such an opinion, but as its accm-acy is doubted by ]\I. de 

 Quati'cfages, we shall now take the liberty of stating more fully 

 our objections to his genus, in order that the facts connected 

 with it may be more thoroughly investigated. It is not our \x\?h. 

 to enter into personal controvers)-, but the validity of a genus is 

 a matter of sufficient importance in zoology to justify om* remarks, 

 more especially as there are some anomalous facts in comparative 

 anatomy connected with it. 



On a careful examination of the description and figure which 

 M. de Quatrefages has given of his new genus, we must again 

 assert, that we can find no external character to distinguish it 

 from Eolis. ^Vith reference to this he remarks, "that Eolidina 

 wants the lateral or labial tentacles, and that all zoologists at pre- 

 sent consider the presence or absence of these appendages as fur- 

 nishing true generic characters." AVe must confess our inability 

 exactly to understand what is here meant by " lateral or labial 

 tentacles." Cuvier, in establishing the genus Eolis, described it 

 to have four to six tentacles ; but subsequent observations have 

 proved that the third pair of tentacles of Cuvier are nothing more 

 than prolongations of the sides of the foot, varying in length in 

 each species and frequently enthely wanting. Later zoologists 

 have therefore, we think very properly, considered Eolis to have 

 no more than fom* tentacles, two dorsal, and two oral or labial. 

 Now the species on which the genus Eolidina is founded has 

 just this number of tentacles placed in the usual manner; it has 

 also the anterior angles of the foot slightly produced, exactly as 

 they appear in several species of Eolis ; indeed so nearly does 

 it approach to some of the English species, that doubts might be 

 raised of its specific distinctness. If then Eolidina is a distinct 

 genus, it must depend upon anatomical characters alone. We are 



