234 Messrs. Aider and Hancock on a new British S])ecies 



stituting Fleming's genus Montagua. It differs entirely from 

 Montagua viridis of Forbes in the form and proportion of the 

 different parts. 



Eolis ]]ellucida. — A very slender and gracefid species, about 

 three-quarters of an inch in length, Anth long slender tcntacula, 

 and the angles of the foot much produced. The body is pellucid 

 white : the branchial papillae long and slightly conical, of a bright 

 rose-vermilion ^nth white tips, set in about five clusters down the 

 sides. This is a critical species, chffering from E. gracilis, no- 

 ticed last year, in the form and colour of the papillae, and from 

 E. nifihranchialis in the more lengthened tentacula and lateral 

 portions of the foot. 



Found on a coralline from deep water at Cullercoats, North- 

 umberland. 



Eolis ciiTta. — The body of this is short in proportion to the 

 other parts. It is about half an inch long, pellucid ; the head 

 and tentacula pale rose-coloured. The branchial papilla? are very 

 long, of a bro^^^lish orange with white tips and a streak of the 

 same in front. They are set in clusters down the sides ; the first 

 large, and three or foui* smaller ones behind nearly coalescing. 

 Dorsal tentacula annulated, sides of the foot much produced and 

 recm-ved. 



Found under a large stone among the rocks at Whitley, 

 Northumberland. 



Eolis concinna. — A very distinct and well-marked species; 

 about hah" an inch long, with nine or ten distaiit transverse rows 

 of pm'plish-brown papillae, tipped with white, on the sides of the 

 back, five in each row : the external surface of these is tinged with 

 pale blue, giving them a metallic lustre. Tentacula linear and 

 smooth, the dorsal longest and inclined forwards. Sides of the 

 foot veiy little produced. Fom* individuals were found together 

 imder a large stone between tide-marks at Whitley. 



We have, dming this summer, had an opportunity of studying 

 the development of the ova in two or three genera of the Nudi- 

 branchia, the phsenomena attending which we find to be veiy 

 similar in all. The fact of their undergoing a complete meta- 

 morphosis, and dm'ing their larva state being provided with a 

 nautiloid shell, is a striking peculiarity distinguishing these from 

 the other families of gasteropodous Mollusca. 



We learn incidentally, in a note to an article on the develop- 

 ment of Apli/sia by Dr. Vanbencden in the ' Annales des Sciences 

 Natm'clles,' that M. Sars has already published an account of the 

 development of some of the Nudibranchia ; but the work contain- 

 ing it not being accessible to us, we are at a loss to know how far 

 cm* observations agree with his, and shall therefore give a short 

 description of the embryo as observed by us. 



