NO, 1 SOOT-RYEN : THE FAMILY MYTILIDAE 101 



Type loc: Callao, Peru. 



Remarks: The description is very short but it agrees completely with a 

 large species of Lithophaga with a median spinelike posterior projection 

 of the incrustation, which in itself is not so heavy as that found in Litho- 

 phaga attenuata. The posterior retractor is dorsal to and separated from 

 the posterior adductor. 



Orbigny gives 71 mm as the total length, with an H/L ratio of 31. 

 Our specimens are distinctly lower, with a ratio of 23 or less. The largest 

 specimen measures 71 mm without the projecting incrustation, which in 

 these specimens shows a tendency to be different on each valve. 

 Occurrence: Orbigny says that this species is very common along the 

 coasts of Peru, living in loose rock or in the bones of whales. The samples 

 at hand were taken in depths ranging from 10 to 18 fms; only one small 

 specimen was obtained by shore collecting. 

 Distribution: Peru. 



Subgenus LEIOSOLENUS Carpenter 1856 



Leiosolenus Carpenter, Catalogue of the Reigen Collection of Mazatlan 



Mollusca, 1856, p. 130. 

 Type of subgenus: Leiosolenus spatiosus Carpenter 1856 (by monotypy). 

 Remarks: The short diagnosis given by Carpenter contains only the sup- 

 position that the animal should have a long excurrent siphon, while the 

 chambers have bilobed pipes. His new species, Leiosolenus spatiosus, was 

 based on only one specimen, 1.5 inches long, and the short description 

 gave as specific character the thin and equally diffused incrustation 

 without projecting parts. On p. 550 in the Appendix, he reported another 

 specimen, 2.3 inches long. L. spatiosus seems not to have been obtained 

 later under that name. 



Morch (1861) reierred Lithophagus rugiferus (Dunker) Reeve 1857, 

 description published by Carpenter (1856), to the genus Leiosolenus 

 on the basis of certain anatomical characters, especially the elongate si- 

 phons; and he also placed Lithophaga patagonica (Orbigny) 1846 in the 

 same genus. This character seems, however, to be more or less common 

 for all species of nearly all groups of Lithophaga. Lamy (1937) gives, 

 as the character separating Leiosolenus from the other groups, the thin, 

 more uniform incrustation without appendages projecting beyond the 

 posterior margin ; but in characterizing the various species referred to 

 Leiosolenus, he mentions several with more or less projecting incrustation. 



Species belonging to this group are found mainly in the Pacific. There 

 seems to be reason to consider Lithophagus rugiferus Reeve 1857 and 

 Lithophaga abbotti Lowe 1935 as synonyms of L. spatiosa Carpenter 



