226 BULLETIN OF THE 



the ribs which seem to connect and bisect their bases ; the intercalary threads 

 appear only in the basal half of the valve and would be wanting in the young ; 

 toward the sides, or rather ends, of the valve, the spines tend to widen into 

 scales concentric to the umbo ; the anterior edges are slightly produced, and 

 the ribs slightly oblique, so that the rib wRich is median to the base when 

 traced to the umbo is a little posterior to the median line there ; there is no 

 median sulcus ; cardinal area and ligamental sulcus wide antero-posteriorly and 

 short in the opposite direction ; cardinal margin simple, pit very shallow ; inte- 

 rior grooved and basal margin dentate, especially toward the middle, to corre- 

 spond with the ribs; shell nearly equilateral. Alt. 9.00; Ion. 5.75; diam. 

 6.00 ; hinge-line 3.50 mm. 



Viilves were obtained by Sic^bee, near Havana, in 450 fms. ; Station 272, 

 near Barbados, in 76 fms.; and by the U. S. Fish Commission at Station 2612, 

 31 miles S. E. by S. | S. of Cape Lookout, North Carolina, in 52 fms., coarse 

 white sand, bottom temperature 67° F. 



The sculpture separates this form from L. confusa E. A. Smith (uvata Jeffreys 

 non Wood), and from the fossil L. ovata Wood, which is usually much smaller. 

 It is perhaps the prettiest species yet described. 



Genus LIM.^A Bronn. 

 Limsea Bronniana, n. s. 



Shell small, white, stout, ovate, rather short and swollen ; with 14-16 

 smooth subequal rounded regular radiating ribs, with nearly equal impressed 

 channels between them ; tliere is a nearly smooth anterior and a smaller smooth 

 posterior area without ribs ; the concentric lines of growth are usually faint ; 

 shell sightly produced at the anterior base ; interior smooth, grooved for the 

 ribs, strongly dentate at the basal margin ; cardinal area narrow, longest in 

 front of the large and strong cartilage pit ; the middle part of the hinge 

 smooth, the angles each with four or five strong teeth, obliquely set ; alt. 3.5 ; 

 Ion. 3.1 ; hinge-line 2.0; diam. 2.5 mm. 



Yar. lata. Shell larger, thinner, less inflated, sculpture less prominent 

 radially, the lines of growth more prominent, the ribs less elevated and 

 numbering 20-26, with the posterior area radiately striate, the interspaces less 

 channelled, the umbo nearly smooth. Alt. 5.3; Ion. 5.2; hinge-line 2.5; 

 diam. 3.1 mm. 



The typical form was taken by the U. S Fish Commission off the coast of 

 the Carolinas, at Stations 2596, 2612, and 2619, in 15-52 fms. ; by the " Blake," 

 in 100 fms., near Barbados. The variety lata was obtained by the " Blake" off 

 Havana, in 452 fms. ; at Station 2, in 804 fms.; and at Station 100, near 

 Havana, in 400 fms. 



This species is immediately distinguishable from L. Sarsi by its sculpture, 

 and by the obliquity of the teeth on the angles of the hinge margin. The 



