278 REPORT ON ALBATROSS MOLLUSC A DALL. 



The septum is thick and fleshy, quite destitute of perforations or 

 orifices except that in which the foot stands. 



Verticordia (Trigonulina) omata Orbigny. 



This species, already known from widely separated regions, was col- 

 lected 90 miles southeast of Cape San Roque, in 20 fathoms, at U. S. Fish 

 Commission Station 275S. 



Verticordia perplicata sp. nov. 



Plate vin, Fig. 1. 



Shell large, strongly plicated radially, with the hinge of Verticordia 

 (restricted) and a coarsely grauulous finely wrinkled external surface 

 of a dark brown color; anterior surface with two or three strong and 

 several smaller obscure radiating ribs which undulate the margin; be- 

 hind these is the strongest broad rib with a rounded top followed by a 

 wide sulcus, then by two somewhat smaller and one still narrower rib 

 with increasingly narrower interspaces; then a wider, stronger, and 

 shorter rib, a deeper sulcus, and lastly by the rounded posterior area; 

 with these principal radii are traces of much finer ones, differing indif- 

 ferent individuals, while the eight primary radii seem pretty constant 

 in position and relative size ; lunule very small and deeply impressed ; 

 behind it in the right valve is a single strong conical or slightly exca- 

 vated tooth, convex below and short; immediately in front of the beaks 

 the hinge line is narrow with a narrow groove for the cartilage and a 

 short, wide, subtriangular ligamentary basis; beaks small, incurved; 

 underneath and a little in front of the cardinal tooth is a small, deep, 

 muscular scar; au tenor adductor scar large, not deep; posterior ditto 

 even less impressed; margins of the valves thin, undulated by the 

 sculpture, not crenulated ; interior pearly white, grooved in harmony 

 with the external sculpture; maximum longitude of shell, 33; max- 

 imum altitude, 35; diameter, (about) 2S mm . 



Hab. — IT. S. Fish Commission Station 2807, in 812 fathoms, mud, near 

 the G&lapagos Islands; bottom temperature 38°.4 F. 



Two nearly complete right valves, fragments of several others, and 

 fragments of two left valves were collected as above stated. When 

 perfect this must be one of the finest species of the genus. The surface 

 is very finely, irregularly wrinkled, with an abundant supply of rather 

 minute pustules, rounded in the specimens but perhaps more pointed in 

 the perfect shell. A more minute description of the hinge must await 

 material in better condition; the data now given are quite sufficient to 

 identify the species. 



