﻿SOI.KNAIA 455 



highest in front, being often cut away at the anterior base, 

 and gradually tapering to the extreme posterior end. In other 

 cases the shell is long rhomboid, and it is sometimes widest 

 toward the posterior end. This species does not seem to 

 show any close relationship with any living form. The char- 

 acter of the posterior sinus of the pallial line is like that of 

 Solenaia, the greatly lengthened foot and burrowing habit are 

 characters in common with that genus, but it is doubtful wheth- 

 er they indicate any close relationship. They are probably the 

 result of similar environment. 



Genus SOLENAIA Conrad. 1869. 



Solenaia Conrad, Am. Jl. Conch., IV, 1869, p. 249. 



Shell greatly elongated, falcate, rather thin, narrower and 

 rounded in front, the upper anterior portion being strongly 

 sulcate, gaping at anterior base and behind, having a strong 

 posterior ridge that ends in a point at the post-base; beaks 

 low; sculpture of slightly double-looped, concentric ridges; 

 epidermis rayless ; hinge line narrow ; teeth rudimentary, being 

 mere vestiges of one or more lamellar laterals in each valve ; 

 dorsal scars numerous, in a line under the hinge; anterior 

 scars faint; posterior elongated; pallial line with a distinct 



posterior sinus. 



According to Fischer the foot is enormously developed for 

 the purpose of burrowing, as in Mycetopoda. It is probable 

 that the mantle is closed behind into two siphons. 

 Type, Mycetopiis emarginatus Lea. 



The genus Solenaia was established by Conrad for the My- 

 cetopus emarginatus of Lea, which Conrad believed was-er- 

 roneously placed in d'Orbigny's genus. He states that the 

 species, which he takes as the type of his genus, has lateral 

 teeth and that it differs also from Mycetopits in having the 

 anterior end reflexed and simple anterior muscular scars. In 

 the Journal de Conchvliologie in 1890. Dr. Paul Fischer m a 

 paper on Mycetopus states that Pere Heude had exammed the 

 animal of Chinese species of this group and ascertamed that 

 it had a foot developed to an extraordinary length and that it 



