460 



TECTURIDiE. 



central, mamillated ; aperture wide, oval, margin regular, 

 entire. 



jE'.r, S. scurra, Lesson, pi. 52, fig. 4, 4, a. Shell, S. 

 scurra, fig. 4, b. 



This genus is founded upon the Patella scurra of Les- 

 son, which is the Acmcea mitra of Eschscholtz, and the 

 Loitia pallida of Sowerby. The margin of the mantle is 

 surrounded by a number of singular, sub-annular, curved, 

 lamellar processes, which resemble gills ; the branchial 

 plume, however, exists in a cervical cavity, as in Tec- 

 tura. 



conica, Gould. 



Species of Scurria. 



scurra, Lesson. 



Genus HELCION, Montfort. 



Shell oval, depressly-conical, cap-shaped, surface with 

 radiating, pectinated ribs; apex excentric, recurved, sub- 

 marginal ; interior covered with a vitreous deposit, margin 

 of aperture crenate ; muscular impression crescentic, in- 

 terrupted in the region of the head. 



Ea^. H. pectinatus, Linnaus, pi. 52, fig. 5. 



The shell of Helcion does not appear to differ generi- 

 cally from that of ScutelUna, except that the interior of 

 the aperture is covered with a peculiar glazed deposit. 

 The nature of the gills has not been well made out ; Dr. 

 Gray, however, states that they resemble those of Patella. 



Genus SCUTELLINA, Gray. 

 Animal provided with eyes. 



