72 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 20 



Lioberus salvadoricus (Hertlein and Strong) 1946 

 Plate 8, fig. 38 ; text-figs. 61-62 



Volsella (Volsella) salvadorica Hertlein and Strong, Zoologica, vol. 31, 



part 2, 1946, p. 73, PI. 1, figs. 7 and 11. 

 Holotype: California Academy of Sciences. Paleo. type collection. 

 Type loc: Off La Libertad, El Salvador; 25 m. 



Remarks: One small (9 mm) dried specimen allowed a superficial inspec- 

 tion of the anatomy after it had been soaked in hydroxide for several 

 hours. The most significant result was the observance of the long siphons, 

 of which the branchial, with a ventral opening, has the same length as 

 the anal siphon. The anterior retractor was placed well before the umbo ; 

 the posterior retractors and the adductor were elongate and placed in a 

 curve in the anteroventral angle. 



The shell shows distinctly raised concentric lines on the anterior part, 

 which are also visible on the inside. This sculpture is not mentioned in 

 the original description but is visible on the figure of the type. The pos- 

 terior part is covered by a filthy mass of mud particles held together by 

 fine threads. There seem to be no hairs on the periostracum, so this cover- 

 ing may be the remnants of a nest. The anterior margin is distinctly 

 grooved. 



Occurrence: Dredged from 2 to 16 fms. The bottom consisted of mud, 

 sand, and shells. 



Distribution: From Bahia Cocos, Boca de Culebra, Costa Rica, north to 

 off La Libertad, Salvador. 



Genus MUSGULUS Roding 1798 



Text-fig. 63 



Musculus Roding, Museum Boltenianum, Part II, 1798, p. 156. 



Syn.: Modiolaria Beck in Robert 1838, 1840. 



Type of genus: Mytilus discors Linne 1767 (subsequent designation by 



Iredale 1915). 

 Remarks: This genus is characterized by the anterior adductor being 

 placed before the umbones and the posterior retractors being continuous 

 and united with the posterior adductor. The extensile posterior part of 

 the mantle forms a long anal siphon, with the lower branchial opening 

 nearly of the same length. For the anatomy, see Pelseneer, 1911, pp. 

 19-20, PI. 5, fig. 5. 



The shell is typically radially sculptured in the anterior and posterior 

 part, without radiating sculpture in the middle. The valves are rather 

 flat, without a distinct keel, but the posterodorsal part is separated from 

 the rest of the valve by a more or less pronounced furrow. 



