204 



site valve in closing; beaks opisthoccelous, inconspicuous. Height, 

 24; length, 39; diameter, 20 mm." 



Type locality: — off the Calif ornian coast in deep water. 



3075 Psephidia cymata 



"Shell small, white, solid, rounded triangular, with inconspic- 

 uous, somewhat anterior beaks, the lunule and escutcheon very 

 feebly indicated; surface with fine concentric but not perfectly 

 regular low threadlike sculpture; periostracum yellowish, rather 

 coarse; hinge of the genus, inner margins smooth, interior disk 

 polished, the pallial sinus small, ascending, the inner extreme 

 bluntly rounded; muscular impressions distinct, ligament small 

 and weak. Height, 5.5; length 6.0; diameter 2.5 mm." 



Type locality: — near Cerros Island, Lower Cal., in shallow 

 water. 



3076 Lyonsia (Allogramma) Amabilis 



"Shell thin, with a pale olivaceous periostracum and pearly 

 interior, the lithodesma small. The sculpture resembles closely 

 that of the type of the group, L. (A.) formosa Jeffreys, from the 

 Canaries, but differs in the following details; the anterior trans- 

 verse ripples, the central nodulous ray, the radial ridge below the 

 posterior dorsal area are more vertically directed; on the latter 

 area there is only faint indication of the radial ribbing which in 

 L. formosa is distinct and minutely spinose; the anterior end is 

 longer than the posterior, while in formosa the reverse is the case; 

 the coloration of the periostracum is olivaceous green while in 

 formosa it is ferruginous brown. Length 23; of anterior end 12; 

 height 15; diameter 12 mm." 



Type locality: — Santa Barbara Channel, Calif., in deep water. 



3077 Lyonsia pugetensis 



"Shell large, thin, pearly under a thin olivaceous gray perios- 

 tracum which is covered with fine radial lines to which fine sand 

 adheres strongly, so that an attempt to remove the sand also de- 

 stroys the greater part of the periostracum; the shell is slightly 

 inequivalve and very inequilateral, the anterior end being much 

 shorter; the periostracum projects over the shelly margin; the an- 

 terior end is evenly rounded, the posterior rostrate, the beaks not 

 conspicuous; the base is convexly arcuate in the middle but is 

 rapidly attenuated toward the rostrum, which is terminally trun- 

 cated; interior pearly, pallial area relatively small within the 

 somewhat irregular unsinuated pallial line; hinge edentulous 

 with a small narrow lithodesma. Length of shell 36; of anterior 

 portion 15; height at beaks 17; maximum diameter 10 mm." 



Type locality: — coast of Washington. 



3078 Poromya (Dermatomya) Tenuiconcha 



"Shell small, thin, olivaceous, the pearly luster showing 

 through the periostracum; equivalve, inequilateral, anterior end 

 shorter, rounded in front; posterior end longer, roundly truncate; 

 beaks prominent, prosoccelous, with a marked but uncircum- 

 scribed depression in the lunular region in front of them; interior 

 pearly, brilliant; margins simple, sharp; hinge in the left valve 

 with a small internal resilium seated on an inconspicuous oblique 

 chondrophore, with a notch immediately in front of it, into which 

 fits a projecting denticle on the corresponding part of the oppo- 

 site valve. Height, 13; length of shell, 16; of anterior portion, 

 6; diameter, 10 mm." 



Type locality: — Off Monterey Bay, California, in deep water. 



