42 THE NAUTILUS. 
Subfamily Lurrarin®. 
Genus TRESUS Gray, 1853. 
+- Cryptodon Conrad, 1837, not Turton; +-Sehizotherus Conrad, 
1853, (about three weeks after Gray) ; type: 
Tresus nuttallii Conrad, 1837. Sitka to San Diego, Cal. 
+Lutraria maxima Midd., 1849, non Jonas, 1844; +L. capax 
Gould, 1850; +L. inflata Dunker, 1853. 
Genus DARINA Gray, 1853. 
Darina declivis Cpr., 1865. ‘ Vancouver;” ‘“ Forbes;” fide Cpr. 
DovuBTFUL OR sPpURIOUS WrsT AMERICAN SPECIES OF MACTRID®. 
There is no typical Mactra or Spisula known from the Pacifie 
Coast. 
Mactra angusta Desh., 1854, from the Gulf of California as figured 
by Reeve, resembles a refined M. californica Conr. Wein- 
kauff’s figure is undoubted californica Conr. not Desh. I have 
not seen authentic specimens. 
Mulinia bistrigata Mirch, 1861, appears to be a mere color variety 
of M. pallida. 
Mulinia Gabbi Tryon, is stated to have come from Lower Califor- 
nia, but has not since been reported from there. It is very 
close to the South American M. exalbida Gray, and as M. exal- 
bida is found near Panama it may reach California. 
Mactrella subalata Morch, 1861, was described from a single worn 
valve obtained at Realejo, Costa Rica. This was probably a 
ballast shell or one in some way transported from the Atlantic 
Coast. Caribbean shells are taken to Panama and other Pacific 
ports for sale to visitors, as I have personally experienced. 
Mactrella alata, of which subalata is a pure synonym, has not 
been authenticated from the Pacific where it is replaced by M. 
exoleta Gray. 
M. (Mactrella) lacinata Cpr., 1856; Panama, Bridges; is probably 
a Mulinia, notwithstanding its reference to Mactrella. Its 
small size (0°7 in.) points toward immaturity. It has not been 
