THE NAUTILUS. 29 



process ; the dental processes small and narrow ; the loop is peculiar, 

 the two supporting arms are appressed and soldered to the wall of 

 the valve for a distance of 8 or 9 mm., so that the loop appears to 

 spring from the valve and not from the hinge ; it abruptly bends 

 upward at a point about 12 mm. in front of the beak, forming a very 

 wide, slender, frail, almost flattened loop with short triangular crura ; 

 the width of the loop is about 12.5 mm., the height of its arch about 

 3 mm., while the crura, which are curved inward parallel with the 

 limb of the arch, are about 3 mm. long. A mesial septum, low and 

 narrow but distinct, extends forward as far as the anterior edge of 

 the adductor scars ; the pallial margin carries minute setae, which do 

 not project beyond the edge of the valve. Length of ventral valve 

 45, breadth 34.5, max. diam. of shell 26 mm. 



Dredged on the southeast coast of Sakhalin Island, Okhotsk Sea, 

 in 64 to 100 fathoms, bottom temperature 30 F. Type, TJ. S. N. 

 Mus., 110, 786. 



The remarkable loop of this species is sufficient to distinguish it 

 from any other of the genus ; the characters mentioned are found in 

 all the specimens. 



Laqueus morsei n. sp. 



Shell thin, smooth, polished, ruddy brown, rounded lozenge- 

 shaped, somewhat attenuated in front up to a 10 mm. wide trunca- 

 tion ; ventral valve with a short beak, entire foramen and short, 

 wid' j , flattened area ; deltidial plates united, but showing a groove 

 at the junction ; dental processes short, triangular, strong, supported 

 by strong props with deep funnel-shaped cavities behind them ; pal- 

 lial sinuses with two inner trunks bifurcating at the anterior third of 

 the valve, and two outer ones branched on the outer side from the 

 beginning; genital glands in two longitudinal lines on each side 

 extending along the middle of the main trunks of the sinuses and 

 barely distally bifurcated ; dorsal valve with a small but well devel- 

 oped hinge-plate, but no cardinal process or cavities under the dental 

 processes ; the septum is short and delicate ; the loop normally 

 formed but extremely slender, except the bight of the recurved por- 

 tion, which is much wider than the rest ; the valves meet in a nearly 

 uniform plane, an extremely faint indication of a truncation in front 

 forms the only approach to a flexuosity. Length of ventral valve 

 32.5, of dorsal valve 29.0, breadth 30.5, diameter of shell 18.0 mm. 



