NO, 1 soot-ryen: the family mytilidae 43 



that the only island "Annaa" he knows is in Polynesia. Because of these 

 doubts, Hertlein and Strong have given the species a new name. There 

 may have been a wrong locality attached to Cuming's type lot, as was 

 often the case, and then the oldest name should be retained. 



This species is easily recognized by the light and varying colors and 

 the hairy periostracum. The apical septum is rather shallow, especially in 

 small specimens. The largest specimen measured has a length of 11.8 

 mm. 



Occurrence: While loose valves are found at many stations, living speci- 

 mens seem to be rare. They are usually found on rocky or stony bottom 

 from the shore down to 50 fms. The material at hand extends the distri- 

 bution considerably. 



Distribution: From Isla de Cedros, Baja California, south to Isla La 

 Plata, Ecuador; Galapagos Islands. 



Genus BRACHIDONTES Swainson 1840 



Text-figs. 24, 27, 32 



Brachidontes Swainson, A Treatise on Malacology, 1840, p. 384. 



Type of genus: Modiola sulcata Lamarck 1819 (not 1805) = Mytilus 



citrinus Roding 1798 = Area modiolus Linne 1767. 

 Remarks: The original description is: "Umbones prominent, not termi- 

 nal ; valves corrugated ; hinge margin considerably angulated, teeth many, 

 small, and crenate." The hinge of the Atlantic Brachidontes modiolus 

 (Linne) shows three large teeth radiating from the umbones and a series 

 of crenulations on the anterior margin, which continue the hinge in a dif- 

 ferent angle. This species seems not to fit the diagnosis completely and 

 there might perhaps be some doubt as to what Swainson's sulcata really 

 was. 



As stated under Hormomya, species referred to this genus have simple 

 bifurcating sculpture, the posterior retractor fastened along the dorsal 

 part of the adductor, not quite terminal umbones, a more or less angulated 

 anterior margin, and toothlike crenulations behind the ligament. Some of 

 these characters may be very difficult to observe, but usually species of 

 Brachidontes are easily separable from Hormomya. The posterior mantle 

 margin is furnished with branched tentacles, though a branching appar- 

 ently is not developed in some of the species. The tentacles or papillae are 

 very contractile and sometimes difficult to see. It seems to be possible to 

 separate five species occurring from Mexico south to the Strait of Magel- 

 lan, but the distinctive characters are not convincing. Some specimens are 



