40 Mr. Jeffreys on British Mollusca. 



a different species. The colour of the auimal differs from that of 

 M. edulis and M. Galloprovincialis m being bright yellow instead of 

 brown ; and the shells are at a glance e(|ual]y distinguishable by the 

 anterior side being extremely gibbous, the posterior or byssal margin 

 being straight or inflected and \imbilicated, the warit of a dorsal 

 angle, the j)ointed extremities, and also by the oblique slope on each 

 side of the lower or basal margins to a point, causing the fanciful 

 but striking resemblance to a bullock's hoof when the valves are 

 placed side by side. The colour of the shell is purplish blue, the 

 epidermis being olive-brown and highly iridescent". The size of our 

 largest specimen is four inches and a half in length, and two and a 

 quarter in breadth. In the Linnsean Collection two shells are still 

 preserved ; one of them being in a tin cradle-shaped box, marked on 

 the lid " Mytilus ungulatus," in Linnteus's own handwriting; the 

 other being loose in the same drawer. Both of these shells have on 

 the inside of one of the valves the number "216" in the same hand- 

 writing ; and this number corresponds with that under which the 

 species is described in the tenth edition of the ' Systema Naturae.' 

 They agree with ours in every respect, except in being somewhat 

 smaller. Dr. Lukis informs me that the "hoof" mussel is some- 

 times, but rarelv, brought to the Guernsey market from a very large 

 reef of rocks about twenty-five miles south of the island, and that 

 such specimens are nearly as fine as those from the Gouliot Caves. 

 The rediscovery of this long lost Linneean species is very interesting. 

 None of the subsequent authors except Poll seem to have recognized 

 it ; and when they attempted to do so, they mistook other, and 

 exotic, species for it. Since the above was written, Mr. Norman has 

 sent me for examination some shells which he, and afterwards Mr. 

 Webster, took at Ilayle in Cornw all, and which clearly belong to this 

 species, as well as a stunted specimen of the form or variety called 

 inciirvatus, found by INIr. Norman at the Land's-End. 



Modiola tulipa, ii. 187. This forms a rude nest by agglutinating 

 together small stones and bits of other shells, in the same manner as 

 the Limce ; and when taken out, it floats on the surface, being either 

 of less specific gravity than the water, or buoyed up by air-cells. I 

 think this is a different species from the M. tulipa of Lamarck, which 

 is exotic, and that the name " radiata,'^ given to it by Mr. Ilanley in 

 Thorpe's ' British Marine Conchology,' ought to be adopted for our 

 shell, A large and dark-coloured variety has been taken by Mr. 

 Norman, as well as myself, plentifully iu Falmouth Harbour. Spe- 

 cimens of this variety attain sometimes the size of two inches and a 

 quarter in length. 



M. cuprea, n. s. 

 Testa ovato-trapezoidea, gibbosa, solidula, nitida, epidermide fulva 

 prismatica, antice flava pilosa, vestita, subtus albida, rugis con- 

 centricis raris irregnlariter notata ; angulo transversali ex aj)icibus 

 ad latus anterius oblique decurrente ; umbonibus obtusis ; lateri- 

 bus, dorsali rectiusculo elevatiore antice rotundato, posteriori ab- 

 rupte truncato, ventrali convexo subsinuato postice declivi, anterior! 



