NO. 5 RHYNCHONELLOID BRACHIOPODS — COOPER 21 



anterior profile broadly and gently convex ; posterolateral slopes 

 moderately steep ; anterior slope long and flattened. 



Brachial valve interior with long, approximately parallel crura; 

 socket ridges stout, grown together with the cardinal process which 

 forms a thickening between the socket ridges at the apex ; median 

 septum stout, short anteroposteriorly, narrow in profile; adductor 

 scars deeply sunk and forming an elongate track on each side of the 

 median septum. 



MEASUREMENTS IN MILLIMETERS 



Brachial 

 Length length Width Thickness 



Holotype 5-2 44 44 i-8 



Paratype U.S.N. M. 274143d 5.3 4.7 4.6 1.6 



Types. — Holotype, U.S.N.M. 274143a; figured paratypes, U.S. 

 N.M. 274143b, c, d, 274168a, 336895a, and 336896a. 



Horizon and locality. — Recent, Eolis Station 340, at 209 fathoms 

 off Fowey Light; several other stations off Fowey Light at depths 

 ranging from 85 to 205 fathoms ; off Sand Key at 75 to 120 fathoms ; 

 off Sambo Reef at 135 fathoms ; off Western Dry Docks, at 80 and 90 

 fathoms ; and off Key West at 1 10 fathoms ; all off Florida. 



Comparisons. — This species is characterized by its narrowly len- 

 ticular profile, the rectimarginate anterior commissure, auriculate 

 deltidial plates, thick cardinalia and short, stout median septum. 



Cryptopora rectimarginata differs from C. gnomon in several re- 

 spects. The latter is quite strongly sulcate, whereas the Florida species 

 is rectimarginate ; C. gnomon is a thicker shell than C. rectimarginata 

 and has a longer median septum and does not have the auriculations 

 on the deltidial plates. Helmcke's species C. boettgeri likewise does 

 not have the auriculations on the deltidial plates and also has a longer 

 median septum than C. rectimarginata. The Australian C. brazieri 

 differs from C. rectimarginata in having a flattened brachial valve, no 

 auriculations on the deltidial plates, and a longer and more delicate 

 median septum. 



A specimen from the Oligocene (Cojinar formation), from Sagua 

 la Grande in Las Villas Province, Cuba (U.S.N.M. 459424a) is 

 strongly suggestive of C. rectimarginata because it has auriculate 

 deltidial plates and the form and profile of the Florida species. 



Cryptopora rectimarginata appears to be a shallow-water species 

 ranging in depth from 75 to 209 fathoms. Cryptopora gnomon, on the 

 other hand, is a deeper-water form. Depth ranges given for specimens 



