NO. 1 SOOT-RYEN : THE FAMILY MYTILIDAE 97 



Lithophaga (Diberus) subula (Reeve) 1857 



Plate 10, fig. 56 



Lithodomus subula Reeve, Conchologia Iconica, Lithodomus, 1857, PI. 



4, fig. 26. 

 Syn.: Lithophaga plumula kelseyi Hertlein and Strong 1946. 

 Holotype: British Museum. 

 Type he: ? 



Remarks: The differences betw^een Lithophaga plumula and the species 

 which here is named Lithophaga subula, are small but constant. Whether 

 they are considered to be specific or subspecific is a matter of subjective 

 opinion. As far as can be decided from the published short description and 

 figures, Reeve's subula is identical with the subspecies named kelseyi by 

 Hertlein and Strong. 



The incrustation, when it is featherlike, is decidedly stronger on the 

 ventral part. Some specimens show the transverse wrinkles of the perios- 

 tracum more common in L. plumula. The dorsal angle is more pro- 

 nounced than that of L. plumula, and the form of the shell is decidedly 

 more elongate and lower ; but the position of the posterior adductor rela- 

 tive to the posterior margin seems to be the most reliable character. 



The largest specimen measures 56.6 mm, including the incrustation. 

 Occurrence: This species is very common along the coast of California 

 to the south of Point Conception and is found on the west coast of Baja 

 California south to Punta Pequena. It is found living from the shore 

 down to 35 fms. The record from Catalina Island, 350-400 fms, must 

 be due to an error, as the piece of cemented broken shells in which the 

 specimens were living has small algae growing on it. In the California 

 Academy of Sciences are preserved specimens from Cosacos River, Alaska. 

 Distribution: Baja California to Point Conception, Alaska. 



Subgenus MYOFORGEPS Fischer 1886 



Myoforceps Fischer, Manuel de Conchyliologie, 1886, p. 969. 



Type of subgenus: Modiola caudigera Lamarck 1819 = Mytilus aris- 



tatus Dillwyn 1817 (monotypy). 

 Remarks: The diagnosis given by Fischer is very short and contains only 

 one character, the crossed projecting portion of the incrustation. This 

 character generally is sufficient for the recognition of the subgenus. Ap- 

 parently this subgenus contains only one species, as the two species men- 

 tioned by Lamy (1937) in connection with Lithophaga aristata, viz., 

 Lithophaga bipennifer Guppy 1877 and Modiola (Lithodomus) excavata 

 De Folin 1867, seem to be referable to the same widely distributed species. 



