(JLYPHIS. 203 



of the shell, its front ends not hooked inward ; shell de- 

 pressed, oblong, truncated or sinuous in front ; surface 

 lacking distinct radiating sculpture ; edge smooth 



Genus SCUTUS Montf. 



Genus GLYPHIS Carpenter, 1856. 



Glyphis CPR. P. Z. S. 1856, p. 223, footnote. Type F. aspera 

 Esch.; Catal. Mazat. Sh., p. 220. Lucapina, in part, H. & A. 

 ADAMS Genera Rec. Moll. 



Few words are sufficient to distinguish this genus from all 

 Fissurellinse and Fissurellidinse : Rhachidian tooth of the radula 

 wide; internal hole-callus of the shell truncated behind. 



Shell ovate, conical, the orifice in front of the middle. The apex 

 spiral, inclined backward in the young, wholly absorbed in the 

 adult. Surface cancellated by radiating and concentric riblets or 

 strine. Internal hole-callus truncated behind or having a pit there. 

 Basal edges of the shell in a plane or the sides slightly elevated ; 

 ends never elevated ; margin crenulated. 



Animal capable of being entirely contained in the shell, resembling 

 Fissurella in external characters. Snout short, ending distaDy in 

 an oval disc with the mouth in the center ; tentacles subulate with 

 black eyes on little projections at their outer bases: epipodium con- 

 sisting of a fringe of short filamentous processes alternately larger 

 and smaller, becoming more obsolete posteriorly where it is marked 

 by little tubercles in place of the filaments. Mantle-edge smooth 

 or papillose, usually rather broad. Central tooth of the radula 

 wide. 



This genus has been confused by all authors (except Carpenter) 

 with Fissurella. It certainly belongs to a distinct subfamily, being 

 more intimately related to Emarginula and its allies. 



The young Glyphis (3-4 mill, in length) has a recurved spiral 

 apex with the fissure in front of it, exactly as in Rimula. The 

 truncation and pit back of the hole-callus are homologous with the 

 septum and pit back of the hole in Puncturella ; a fact not hereto- 

 fore noticed. Glyphis may be considered the highest or most modi- 

 fied form of the subfamily Emarginuttnce, and Scutus the lowest or 

 most archaic. 



It is doubtful whether the fossil group Atractotrema of Cossman 

 (Mem. Soc. Roy. Malac. de Belgique, xxiii, p. 31) should be referred 

 to Glyphis or to Rimula. 



