THE NAUTILUS. 69: 
seems to rest upon the presence or absence of a septum. As this 
generic character may be preseut or absent in some of the shells 
found in the same place, an interrogation naturally arises as to the 
value to be placed upon the septum in separating approximate forms 
into two different subfamilies, the Mytilinze and Dreissensinz. 
NOTE ON SEPTIFER BIFURCATUS CONRAD. 
BY H. A. PILSBRY AND w. J. RAYMOND.’ 
Among the shells brought home by Thomas Nuttall from his jour- 
ney to the Pacific coast and the Hawaiian Islands, were specimens 
of a mussel which Conrad named Mytilus bifurcatus.’ Two speci- 
mens of this species were presented by Nuttall to the Academy of 
Natural Sciences,’ where they are still preserved. 
Conrad gave the locality “ Sandwich Is.” for his species; but the 
specimens were probably from California. In the Conchologia Icon- 
tea, Vol. 10, Mytilus, pl. 9, fig. 41 (1851), Reeve figures and de- 
scribes a specimen from Cuming’s collection as Mytilus bifurcatus 
Conrad, giving no locality. I do not know that the interior of this 
shell has been examined; but Nuttall’s shells in the Academy col- 
lection prove to belong to the genus Septifer, having a well-developed 
septum or little deck across the apices of the valve cavities. There 
is no especial reason for believing Reeve’s specimen to be a true 
Mytilus; but if they should be, the name MV. bifurcatus Reeve can- 
not be retained, on account of the conflict with Conrad’s prior J. 
bifurcatus. 
As Mrs. Williamson’s article (above) shows, Californian conchol- 
ogists find two species excessively similar externally upon the Cali- 
1Tn placing Mr. Raymond's name with my own, it should be mentioned that 
he is directly responsible only for the passages placed in quotation marks ; 
though indirectly for the positions taken in the remainder of the article. —H. 
af; P: 
* Journal of the Academy of Natural Sciences of Philadelphia, eS 1834, 
p- 241, pl. 18, fig. 14. 
3 Neither of these shells seems to be the original of Conrad’s figure, and 
probably that particular shell has been smashed and discarded, the specimens 
having been glued to a card and consequently exposed to such accidents. A 
nearly complete series of Nuttall’s shellsis in the Academy Collection, includ- 
ing some not described by Conrad. 
