— 50 — 



off after it was arranged for drawing.) I illustrate this shell to show 

 that such a Mytilus existed in the latest stage of the California coal- 

 epoch, with a strong suspicion that it has already one or two names. 

 Gabb's Septifer was described from one young specimen found at Tejon, 

 very nearly in the same strata, and it is not unlikely that he was 

 mistaken in the generic character, but if proved correct the specific 

 name suits this species as well. There is also Conrad's Mytilus 

 inezensis, assigned to the Miocene Tertiary, which prima facie seems 

 most probable, though there is room for doubt. This has not lately 

 been confirmed among large numbers of Miocene fossils handled by 

 me, and if found in the Miocene will probably be found to be the living 

 M. bifiircatus, which also has its Septifer bifurcatus coexisting. In 

 doubt as to the true value of the slight distinction between the two 

 genera, I leave their correct names to be decided by future discoveries. 

 Several valves found in the head-wall of the California Coal Mine, 

 near Huron, Fresno County, associated with Gyrodes dowelli White, 

 and other species of Cret. B. They had a brown color externally, 

 but were much broken up and fragile, so that no good one could be 

 illustrated. 



Crenella santana n. sp. (PI. Ill, Fig. 40.) 



Shell modioliform, with forty to fifty faint ribs, radiating from the 

 beaks toward the periphery. Beaks about one sixth of total length 

 from anterior end, a little raised; dorsal margin slightly convex; basal 

 a little concave at middle; ends broadly rounded. Length, 0.32 inch; 

 height, 0.20; diameter, 0.12. From base of Ft. Loma; Cretaceous, Div. 

 A; two found by Mr. Fairbanks. 



Apparently the same species was found in the Santa Ana Mts., by 

 Dr. Bowers, but they were so eroded that no definite sculpture could be 

 seen, and were three or four times the size of the San Diego specimens. 



Megerlia dubitanda n. sp. (PI. IV, Figs. 48, 49.) 



Lower valve transversely oblong, moderately convex; its anterior or 

 basal margin nearly straight; rayed with fort}" to fifty close-set ribs; 

 outer margins curved downward, chiefly opposite beaks, for one fourth 

 of the circumference. Upper valve more convex, with coarser ribs, 

 only about half as many as above. Beak unknown, not very promi- 

 nent. A shallow median furrow, with low ridges at sides. Some of 

 the ribs become divided near margin. Height from base, 1.12 inch; 

 length, 1.12; diameter, 0.50. One lower valve is 1.75 long (trans- 

 versely), 0.50 deep. 



The genus is, of course, only surmised from external characters. It 

 is probably different from that of the next species, but both occurred 

 together, especially at La Jolla, in Cret. A, though this was commonest 

 at base of Pt. Loma, Mr. Fairbanks finding six or more valves. 



