426 Dr. J. Gwyn Jeffreys on 



Oilier species of Amussium in the European seas are : — 

 A.fenestratum, Forbes (Pecten), the lower valve of which is his 

 P. concentncus, Philippi's P. antiquatus, Acton's P. PhilippUy 

 E. von Martens's P. Actont, and Tiberi's P. incequisculptus ; 

 and A. striatum, Jeffr. MS. To this genus also belongs 

 Pecten cristatus of Bronn, a fossil of the older Italian Ter- 

 tiai'ies. 



Lima ovata, S. V. Wood. 



Lifiia ovata, S. V. Wood, Monogr. Crag Moll. (Palpeont. Soc. Publ.), 

 vol. ii. p. 48, tab. vii. fig. 5. 



Shell broadly oval, with a somewhat oblique outline, 

 convex, ratlier thin, semitransparent, and glossy : scidptm-e, 

 about 50 fine longitudinal ribs, which are of a proportionate 

 size throughout ; tiiese are crossed by numerous and close-set 

 concentric strifB, giving the crests of the ribs a slightly notched 

 or prickly appearance : colour white, with a yellowish-brown 

 tint in a living specimen : margins rounded and more or less 

 scalloped in front, with a gentle curve at the sides : hedks 

 prominent, and having a blunt or tubercular nucleus : ears 

 very small and narrow, obtuse-angled : cartilage minute : 

 ligament narrow : hinge-line straight : hinge-plate spindle- 

 shaped, with a plain or smooth edge: cartilage-pit triangular 

 and narrow : inside glossy, exhibiting the reverse of the ribs 

 but no central or other furrow. L. 0'2. B. 0'125. 



One living specimen and three valves, besides a few frag- 

 ments, from Station 12, 1450 fathoms. One fragment is much 

 larger than the others, and represents a size double that which 

 is stated in the above description. 



I have described anew this species, for the purpose of giving 

 more details than are found in Mr. Wood's diagnosis of the 

 Crag fossil and of comparing with it what I believe to be the 

 now living or recent form. The oblique contour is observable 

 in some of the Crag specimens. These are certainly thicker 

 than living specimens ; but such difference may be explained 

 by the nature of the former and present habitats. The Coral- 

 line Crag, in which L, ovata occurs, was probably formed at 

 a depth not exceeding 50 fathoms. I have showntfin the 

 cases of Mactra solida and its variety elliptica (' British Con- 

 chology,' vol. ii. pp. 418, 419), as well as of Buccinum unda- 

 tum and many other Mollusca, that shells of the same species 

 from deep water are invariably thinner than those from shallow 

 water. The partial absence of ribs or stride in the Crag speci- 

 mens is observable also in the variety leviuscula of Lima 

 elliptica ; and even Crag specimens of L. ovata vary in that 

 respect. In my specimen of L. ovata from Monte Mario the 



