NO. 1237. SYNOPSIS OF THE LUCINACEA—DALL. 827 



sions normal, strong; inner m .rgins finely crenulate. Alt. 7.6, lat. 8.3, 

 diam. 6 mm. Most specimens are one-third smaller. The varieties are 

 chiefly in asymmetry, some specimens having the beaks very posterior, 

 especially in the young; the radial ribs are sometimes bifurcate dis- 

 tally, and the concentric sculpture varies in strength and condensa- 

 tion. The P. rancelhivh Philippi is the Pacific coast analogue. 



PHACOIDES (HERE) RICHTHOFENI Gabb. 



(Plate XL, figs. 7, 9.) 



Views of a young specimen from 15 fathoms, gravel, on the north 



side of Catalina Island, California, are given. The adults have a much 



more cavernous lunule. The figured specimen measures: alt. 13.0, 



lat. l-t.S, diam. 7.. 5 mm. 



PHACOIDES (CAVILUCINA) LAMPRUS, new species. 

 (Plate XXXIX, fig. 9.) 



Shell of Dosinioid form, solid, nearly orbicular, slightly convex, 

 sufl'used with yellow or pinlv, strongest on the interior of the shell, or 

 plain white; beaks subcentral small, prosogyrate, with a small, more 

 or less excavated lunule usually almost confined to the right valve; 

 sculpture chiefly of fine, low, rather sharp, concentric threads with 

 occasional sulci, due to resting stages, near the margin in senile speci- 

 mens; radial sculpture comprising more or less microscopic striula- 

 tions and a broad shallow flexuosity of the posterior dorsal area, which 

 is often obsolete; dorsal areas inconspicuous; hinge and muscular 

 impressions normal, basal margins very minutely crenulate. Alt. 

 23.5, lat. 23.5, diam. 10.5 nun. 



The figured specimen is from La Paz, Lower California. This species 

 has lono- ])een known in Pacific coast collections as Luchia excavata 

 Carpenter, a name preoccupied in the genus, but a camera lucida draw- 

 ing of his type of excavata by Carpenter shows that his type specimen 

 was a young valve of TIer<^ rklithofenh, afterwards described from 

 fossil specimens by Gabb. The amount of excavation of the lunule 

 in P. lampruH varies in individuals, and between the two valves. It 

 seems to be relatively greater in the young, contrary to the rule in 

 richthofeni The solidity and thickness of the shell are notable. 



PHACOIDES (CAVILUCINA) LINGUALIS Carpenter. 



(Plate XXXIX, fig. 7.) 



This species, I believe, though abundant in the Gulf of California, 

 has never been figured. Therefore I thought it useful to illustrate it. 

 It is the west coast analogue of P. trlsulcatus Conrad. Phacoides {C.) 

 prolongatus Carpenter appears to be distinct, from the specimens I 

 have seen, all of which are poor. It is smaller, higher in pr()i)()rtion, 

 and with more prominent beaks. 



