MUSEUM OF COMPARATIVE ZOOLOGY. 217 



Pecten dislocatus Sat. 



Pecten dislocatus Say, Journ. Acad. Nat. Sci. Phil., ii. p. 260, 1824. 



Collected eight miles S. S. W. of Sand Key light, in 125 fms., by the steamer 

 " Bache," in 1872, at Station 36, in 84 fms., and by Sigsbee, off Havana, in 

 182 fms. The specimens obtained were dead, and perhaps disgorged by some 

 fish, as this species is known to prefer water of moderate depth. No living 

 specimens were obtained. The relations of this species to P. nucleus Born are 

 rather close, and it is a question I have not time at present to investigate 

 whether Say's name is the first which has been given to this shell. Though 

 allied to F. i^urpuratus Lam., it seems distinct from it. 



Pecten phrygium, n. s. 



Shell of the general form of P. asper Sby., flattish, oblique, both valves 

 similarly sculptured ; left valve with about eighteen ribs with nearly equally 

 wide interspaces ; these ribs have three sharp thin keels upon them, a median 

 and two lateral ones, which project on the distal margin of the valve, and, with 

 the similarly projecting points of four intercalary smaller keels, fimbriate the 

 margin in a remarkable manner ; when perfect there are rounded scallops 

 thrown from keel to keel close together, like the edges of a roll of coins, which 

 hide all the keels except the extreme edge of the median keel of the ribs, 

 which, without projecting much, forms a raphe, connecting the scallojied sur- 

 face ; the material of the scallops is very fragile, and when worn away leaves 

 a totally different surface, which in this case shows a multitude of sharp thin 

 scales (the bases of the scallops) zigzagging from keel to keel and imbricating 

 the keels ; the ears are moderate and subequal, there are about five distant 

 narrow ridges on the anterior and two or three on the posterior ear of the left 

 valve, with finer intercalary thread.s ; the right valve has the ridges on the 

 posterior ear scaly, and the byssal fasciole transversely concavely ridged ; there 

 are four or five free spines to the pectinium ; the cardinal margin is straight 

 and internally strongly vertically striate, as in very young specimens of 

 Janira or Amusium. Height of largest valve, 36.5 ; width, 36.5 ; cardinal 

 margin, 19.0 mm. Umbonal angle about 100°. 



Dredged living at Station 32, in 95 fms., north of Yucatan Banks, in N. Lat. 

 23° 32' and W. Lon. 88° 5'; bottom temperature not noted, but probably about 

 60° F. 



Dead valves were found at Station 45, in 101 fms., bottom temperature 

 61°.75 F. ; at a depth of 127 fms., off Havima, by Sigsbee; and off Grenada, at 

 Station 244, in 792 fms. It is probably a dweller in about 100 fms. when 

 living. 



The very remarkable sculpture of this species sufficiently distinguishes it 

 from any other, and specimens not fully adult may be recognized at once by 

 the fimbriated basal margin of the valves. It is related to P. Philippii Recluz 



