Fam. 1, Plate -27. 



Fig. 5. 

 IDALIA LEACHII, Alder and Hancock. 



I. alba ; tentaculis gracilibus ; margine palliali filamentibus perlougis, anticis 4, lateribus utrinque 

 6, instructor filamentibus dorsalibus numerosis, ordinibus 3 vel 5 ; brancbiis 11, pinnatis, insequalibus. 



Malta elegans, "Leuck," Aldei^, in Trans. Tynes. Club., p. 112. 



Hab. Torbay, Mrs. Griffiths, (Mus. Leach). Whitburn, Durham, Rev. G. Cooper Abbes. 

 Hebrides, G. Barlee, Esq. 



Body about an inch long, convex, Nvhite tinged with rose-colour from the viscera shining 

 through. Tentacles linear, tapering, long and slender, finely laminated posteriorly nearly to 

 their base ■ with four filaments in front, two near the base of each, tentacle, set on the pallial 

 margin, which passes close in' front of the tentacles, and circumscribes a small area on the back. 

 Lateral filaments six on each side, long and slender, the last bifid ; attached to the pallia! 

 ridge. There are numerous filaments on the back ; the central row containing three, and the 

 two sublateral rows three or four filaments each : there are occasionally two additional rows 

 developed posteriorly, containing one or two filaments each ; making in all five rows. 

 BranchicB consisting of eleven slender pinnate plumes, largest in front and becoming small 

 behind, where the circle is incomplete. The anterior plume is bifid for about two thirds the 

 length : the two posterior plumes are also bifid. Foot broad and fleshy, tapering to an obtuse 

 point posteriorly. 



The spicula are large, linear-fusiform and more or less bent in the centre, around which 

 they are strongly nodulous : one or two rings of small nodules occur also on other parts of 

 the surface. 



We described this species under the name of Idalia elegans in the Catalogue of the 

 Mollusca of Northumberland and Durham, on the authority of a specimen so named in 

 Dr. Leach's Collection in the British Museum, expressing, at the same time, a doubt of the 

 correctness of the appellation. Further observation has convinced us that this is not the 

 species of Leuckart ; and having recently taken specimens of what we think to be the true 

 Idalia elegans, we have given the name of Leachii to the animal now under consideration. It 

 comes very near to the I cirrigera of Phillippi, from which, however, it differs in the number 

 of filaments and branchial plumes. Dr. Phillippi's figure also represents the dorsal area 

 much broader than it is in our animal. 



Four examples of this fine Idalia have occurred: — the British Museum specimen already 

 mentioned, sent from Torbay by Mrs. Griffiths; a small individual, half an inch long, obtained 

 by Mr. Abbes from the fishing-boats at Whitburn ; and two specimens got by Mr. Barlee in 

 one of his dredging excursions to the Hebrides, which are now, by his liberality, in our 

 possession. The Whitburn specimen, the only one we have seen in a fresh state, and from 

 which our figure is taken, was unfortunately dead when it reached us. The drawing is, 

 consequently, less perfect than it might have been had we seen the species alive. 



