250 Mr. T. Edmondston on a new species of Pecten. 



E. splendidum, Ehr. 



Coast of Norway, by Ehrenberg. 

 E. racemosum, Ehr. =r Sertularia racemosa, Cavolini. 



Bay of Naples. 



VI. Genus Coryne, Gsertner. 



Polyps without polypidoms ; tentacles all alike, scattered. 

 C. squamata, MuUer. 



Coasts of Belgium, England, the Baltic, &c. 

 C. aculeata, Wagner. 



Coast of the Adriatic. • 



VII. Genus Hydr actinia, nov. gen. 

 Polyps without polypidoms ; tentacles in one row. 

 H. lactea. Van Bened. = Synhydra parasitica, De Quatref . 



Coasts of Belgium, Normandy, Brittany, the port of Cette ? Bay 

 of Naples. 

 H. rosea, Van Bened. 

 Coast of Belgium. 



We are not sufficiently acquainted with the genera Echino- 

 chorium"^ of Hassall and Corimorpha of Sarsf to assign their 

 place. We prefer simply to mention them. 



Unless we are mistaken^ the two proposed genera (Eleutheria) 

 and Synhydra should therefore not be inserted in the zoological 

 system, the one being a transitory form, a larva ; and the other 

 having been already described under another name. 



( 



XXXI. — Description of a new Species of Pecten. By Thomas 

 Edmondston, F.B.S.E. & L. 



PecSten MacGillivraii, Edmondston. 



Sp. Char. — Shell orbicular, white, the upper valve with twenty, 

 the lower with eighteen ribs, which, with the interstices, are quite 

 destitute of longitudinal or transverse strise ; each interstice ter- 

 minates in two acute trigonal teeth. 



This highly beautiful Pecten, which can never be confounded 

 with any other British species, and which, so far as I can ascertain, 

 is equally distinct from any hitherto described, is of a pure snowy 

 white colour, a slight tinge of pink near the umbo on the upper 

 valve alone excepted ; the surface shining with a satiny lustre ; 

 the upper valve is more convex than the lower and has twenty 

 ribs, the lower valve has eighteen ; in both the ribs are rather de- 

 pressed and evanescent towards the umbones, which are acute ; 



* Annals of Natural History, vol. vii. p. 371. 

 f Beskivelser og jagttagelser. Bergen, 1835. 



