1863.] MR. A. ADAMS ON THE LIOTIIN^ OF JAPAN. 71 



5. Description of two Species of Shells collected by 

 Dr. Lyall, of H. M. Ship ' Plumper,' at Vancouver 

 Island. By W. Baird, M.D., F.L.S. 



Leda fossa, Baird. 



L. testa elongata, ovali, antice tnulto breviore, rotundata, postice 

 elongata, in rostrum subacutum producta, transversim unduJato- 

 costata, in latere antico fossa transversa notata ; umbonibus 

 prominulis, margine ventrali rotundato ; intus IcBvi ; epidermide 

 tenui, lutescente, nitida induta. 

 Long, rather more than g inch ; lat. rather less than 5 inch. 

 Hub. Esquimau Harbour, Vancouver Island ; dredged in from 10 

 to 15 fathoms water, by Dr. Lyall, of H. M. S. 'Plumper.' {Mus. 

 Brit.) 



This little shell is of an elongate form, much produced posteriorly ; 

 and near the anterior extremity it is marked by a longitudinal depres- 

 sion or pit, upon which the ribs are nearly obsolete. 



NucuLA lyalli, Baird. 



N. testa ovato-triangulari, tumida, crassa, umbonibus prominulis, 

 antice breviore, subrostrata, postice declivi, elongata, margine 

 ventrali rotundato, epidermide olivacea induta, longitudinaliter 

 utrinque costata, costis fortibus, medio divaricatis ; intus mar- 

 garitacea ; margine ventrali sub cost ato ; dentibus anticis ad 

 numerum undecim, posticis novemdecim. 

 Long, rather more than | inch ; lat. rather more than | inch. 

 Hab. Esquimau Harbour, Vancouver Island; dredged by Dr. Lyall, 

 H. M. S. ' Plumper,' in from 8 to 10 fathoms. (Mus. Brit.) 



This very interesting species is the fourth of this peculiar divaricately 

 ribbed group which has been discovered in a recent state. The three 

 others are Nucula divaricata and N. castrensis of Hinds, and N. mi- 

 rabilis of Adams and Reeve. This species approaches very nearly to 

 the fossil species from the Crag, N. cobboldice, but differs from it in 

 being less transversely ovate, in having the beaks more prominent, the 

 posterior row of teeth in the hinge fewer in number (in iV". cobboldice 

 they are 22), and in the costations being stronger in proportion to 

 the size of the shell, and much fewer in number. It was with some 

 hesitation that I decided upon describing it as a new species ; but these 

 marks, the size, and the habitat all induce me to consider it as distinct. 

 I have named it after Dr. Lyall, of H. M. S. ' Plumper,' who has 

 sent us only one specimen. 



6. On the Genera and Species of Liotiin^ found in 

 Japan. By Arthur Adams, F.L.S., etc. 



M. Morch imagines Cyclostrema to be allied to Scala ; and the 

 shell undoubtedly bears some resemblance to that genus. In Liotia, 

 according to my observations, there are no intertentacular lobes, but 



