NO. 1 soot-ryen: the family mytilidae 41 



cies are found mainly in tropical or subtropical waters. From the west 

 coast of America only two species are recognized, as the statement of 

 Clessin (1889) that Septifer crassus Dunker 1853 should be found in 

 Peru is erroneous. There is, however, a possibility that specimens referred 

 to S. bifurcatus Conrad constitute more than one species. 

 Key to the west American species : 



Periostracum strong, dark, without hairs ; ribs 



generally strong, irregular, hinge with at least 



one single or compound large tooth bifurcatus (Conrad) 



Periostracum thin, light-colored, with 



long hairs; ribs fine, granulated; hinge 



with smaller teeth; light and bright-col- 

 ored small species zeteki Hertlein and Strong 



Septifer bifurcatus (Conrad) 1837 

 Plate 4, figs. 19-20; text-fig. 33 



Mytilus bifurcatus Conrad, Jour. Acad. Nat. Sci. Phila., vol. 7, 1837, 



p. 241, PI. 18, fig. 14. 

 H oh type: lost. 



Type loc: Sandwich Islands, ?California. 



Remarks: From Conrad's short description it is impossible to tell if his 

 species is a Septifer or not. The color of his shell is stated to be dark 

 purple and the habitat Sandwich Islands (Ouau, etc.). Carpenter (1864, 

 p. 527) says: "The type is lost; the figure and description would suit 

 many species. It is allocated, in Mus. Cum., to the Californian Septifer; 

 but by Pease to a Sandwich Island Mytilus." 



Though the type may have nothing to do with the Cuming Collection, 

 the name bifurcatus has been used for the California Septifer. Dunker 

 (1853) used the name Mytilus trifurcatus. Pilsbry and Raymond (1898) 

 say that specimens of Mytilus bifurcatus described by Conrad and col- 

 lected by Nuttall were presented to the Academy of Natural Sciences in 

 Philadelphia, where they are still preserved. They probably were collected 

 in California and they proved to be Septifer. But the allocation of the 

 name bifurcatus to the genus Septifer cannot be said to be settled. 



The outer form of this species is as variable as that of other intertidal 

 mytilids. The keel from umbo to posteroventral angle is generally very 

 pronounced and the ventral part flattened. The radiating sculpture is 

 strong posterior to the keel, with the upper ribs bent dorsalward ; the 

 ventral ribs are weaker; all ribs are irregularly furcating. The perios- 

 tracum is dark, blackish. The anteriorly placed umbones are strongly 



