338 REPORT OF NATIONAL MUSEUM, 1897. 



Localities. Coast of Yucatan, North Atlantic (stations 2358, 2530, 

 2614), 10 to 956 fathoms. 



POLYSTOMELLA CRISPA Linneeus. 

 (Plate 80, fig.- 3.) 



Lenticular, strongly biconvex, peripheral margin angular; septal 

 pores in a single row, large, and closely set; umbilici tilled with clear 

 shell-substance more or less porous. Diameter, about 0.7 inm. (- 3 \ inch ) 



Locality. Not recorded. 



Subfamily IJ^TTJMIVITJIl.ITIlSrjE. 



Test lenticular or complanate; lower forms with thickened and finely 

 tubulated shell-wall, but no intermediate skeleton; higher forms with 

 inter septal skeleton and complex canal system. 



Genus AMPHISTEGINA. 



Test spiral, lenticular, inequilateral; chambers equitant, the alar pro- 

 longations on one side simple, on the other divided by deep constric- 

 tions so as to form supplementary lobes. Shell-wall thickened near the 

 umbilicus and finely tubulated, but presenting no true canal system. 



AMPHISTEGINA LESSONII d'Orbigny. 

 (Plate 80, fig. 4.) 



Lenticular, somewhat unequally convex on the two sides; margin 

 angular; surface smooth; segments numerous, narrow, bent, simple on 

 the upper side, but constricted on the inferior side, and sharply bent 

 backward; aperture on the under side of the last segment. Diameter, 

 about 1.5 mm. (^ inch). 



Localities. North Atlantic, coast of Yucatan, Gulf of Mexico (sta- 

 tions 2415, 2629, 2641, 2363, 2370), 9 to 1,169 fathoms. 



