192 



BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



compartments are thin and part very easily. Without the opercular 

 monly harbors Balanus rostm-tus apertus. 



The sponge is the same friable species of soft texture which com- 

 monly harbors Balanus 7'ostratus apertus. 



The United States National Museum collection is rich in specimens 

 from the Aleutian Islands, and as far south as Puget Sound, but 

 the southern limit of the species remains to be ascertained. Darwin 

 records it from the Columbia River. It probably occurs in northern 

 California. The locality " Golf e de Georgie" (Paris Museum, Gru- 

 vel) also quoted by Kriiger, evidently means the Gulf, or more prop- 

 erly Strait of Georgia, east of Vancouver Island, British Columbia, 

 where Dr. A. Agassiz collected many years ago. On the west, it ex- 

 tends as far south as Hakodate in southern Yesso (Hokkaido), and 

 probably farther south, as it was taken by Mr, H. Loomis, whose 

 material is chiefly from Jedo Bay, in middle Japan. The record 

 Cochin China, in the Paris Museum, can hardly be accepted Avithout 

 confirmation. It seems most improbable. 



HESPERIBALANUS, new subgenus. 



Balani with poreless walls and basis, the radii Avith thick, septate 

 edges ; opercular valves as in the Balanus crenatus group. Mandible 

 with the fourth and fifth teeth short and broad, lower edge shortly 

 hairy. Maxilla with few spines. 



Type. — B. hesperius. 



