THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



No. 83. MARCH 1844. 



XXI. — Description of a new Genus of Nudibranchiate Mollusca, 

 with some new Species of Eolis. By Joshua Alder and 

 Albany Hancock, Esqrs. 



[With a Plate.] 



Although the British Fauna has been investigated more care- 

 fully perhaps than that of any other country, fortunately for the 

 naturalist of the present day, much still remains to reward his 

 search, especially among the Marine Invertebrata of our island : 

 of this the Nudibranchiate Mollusca afford a striking example, 

 th^ number of known British species having been nearly doubled 

 within the last few years. We now have the pleasure of offering 

 a further contribution to the knowledge of this interesting tribe. 



Gen. Venilia*. 

 Body limaciform, ovate-oblong, depressed, tapering to a point 

 behind. Head anterior and inferior, covered by a semicircular 

 veil; mouth with a pair of corneous jaws. Tentacula 4, linear, 

 non-retractile ; 2 dorsal, erect, and 2 small oral ones attached 

 to the sides of the veil. Branchim papillary, elongated, ar- 

 ranged on a projecting margin down each side of the back, 

 with a few papillae extending round the head in front of the 

 dorsal tentacula. Anus posterior, on the medial line of the 

 back. Aperture of the generative organs on the right side. 



This curious animal unites several of the characters of the two 

 principal divisions of the order Nudibranchiata, and may be con- 

 sidered, in some respects, intermediate between them. In its 

 general appearance it reminds us at once both of Eolis and Eu- 

 plocamus. With the latter it agrees in general form, and in the 

 broad, flattened back, produced at the sides, and surrounded by 

 appendages which are continued round the front of the head. 

 The form of the head and veil is also similar ; and the posterior 

 dorsal position of the vent indicates a still nearer approach to 

 this and the other genera of the family Doridce, from all of which 



* The name of a wife of Neptune. 

 Ann. ^ Mag. N. Hist. Vol. xiii. M 



