MAZATLAN BIVALVES 167 
It is so easy inthin Anomiade to see the muscular scars one 
expects, that I had sketched 3 scars for this species to shew 
the difference in arrangement from those of A. lampe, of which 
many conchologists had considered my valve a variety. Having 
however found a pair, and being struck by the Y-shaped notch 
at the cardinal end of the hole, I re-examined the scars, and 
found the supposed third to be only one of those non-muscular 
impressions which are very liable to deceive beginners till they 
have learnt from books what they ought to look for. Shell 
extremely like Anomia lampe (smooth var.) ; from which it is 
known at once by the brown disk, inside which is a very faint 
white disk, with the extremity rounded, not triangular. It is 
‘known from P. foliata by the entire absence of radiating 
strie, which are very conspicuous in young shells of. that 
species. A remarkable feature in this shell is the sharp white 
lamina, (or clavicle,) which runs from the hinge in the lower 
valve, near the hole but not parallel with it, losing itself in a 
thin white deposit in which is the muscular scar. This clavicle, 
or lengthened support to the cartilage plate, is also seen in P. 
Cumingii, large, rounded, and running in a straight line to the 
muscular scar. It is more or less developed in some other 
species of the genus; but is remarkable in this for its length, 
direction and sharpness. Jong. 1°12, lat. 1°46, alt. °16. 
Hab.—Mazatlan ; one pair and a valve with Anomiz; L’pool 
Col. 
Tablet 750 contains the pair. 
Genus ANOMIA, Linn. 
219. ANOMIA LAMPE, Gray. 
Proc. Zool. Soc. 1849, p. 117 ;—B. M. Cat. Anom. p. 19, sp. 
14.—C. B. Ad. Pan. Shells, p. 244, no. 377. 
This shell in its ordinary state would hardly be known by 
the meagre description in the B. M. Cat. ; but the very numer- 
ous finely grown specimens sent in this collection give oppor- 
tunity to record its leading features. Many hundreds were 
sent carefully packed ; but most have been broken since they 
came to this country. There was also a box of valves, many 
of them extremely brilliant, from which I picked the valve of 
P. eclaviculata; doubtless there were many other treasures in 
it, but it was unfortunately sold off to make ladies’ fancy work 
before I had an opportunity of examining it. % 
