﻿STREPTOIUIYXCIR'S. 



83 



&c.,' Professor rhillips rcdescribcs and figures (pi. xxvi, fig. 10S) what he takes to be 

 Sowcrby's so-termed species, but which appear to me (in part at least) to be small imper- 

 fect distorted casts or impressions of Sfr. crcnintria. 



Streptorhtncb us gigas, M'Coy (sp.). PI. XVI, figs. 1 — 3. 



Lept.ena (Strophojiexa) gigas, M'Coy. British Pal. Foss., pi. ii A, fig. 7, 1852. 

 ? Lept.ena spathulata, F. Roemer, in Dunker mid v. Meyer's Palaeontograpliica, vol. 



v, p. 98, pi. xv, fig. 2, 1852. 



Spec. Char. Elongated, elliptical, truncated by a straight hinge-line, which is equal 

 to the width of the shell. Ventral valve much depressed, and slightly convex near the 

 margin. Surface radiated with very numerous fine, close, obtuse striae, separated by 

 numerous fine, finely punctured impressed lines, every fifth, seventh, or ninth of which 

 seems larger than the rest ; about sixteen striae in two lines at an inch from the beak, 

 fifteen in the same space at the margin three inches from the beak ; cardinal area broad. 

 Proportions variable. 



Length 3| inches, width 2^ inches. 



Obs. Of this large species (?) I have seen several internal casts of the ventral valve 

 from the Devonian shales or brown grits of Looe and Polruan, in Cornwall, and from 

 whence the specimen showing traces of the shell-surface or sculpture was described 

 and figured by M'Coy. Internal casts of the ventral valve in Mr. Pengelly's collection 

 show two large pyriform muscular scars (in relief on the cast), which are due to the 

 divaricator, and perhaps ventral adjustors of Hancock, while in the centre between these 

 large scars may be seen an elongated oval one referable to the adductor or occlusor 

 muscle. Professor M'Coy states that " this gigantic species in its elongated, elliptical, or 

 sub-trigonal form arising from the narrow rounded front, precisely agrees with Orthis 

 mbaraclnioidea of MM. d'Archiac and De Verneuil (Geol. Trans., 2nd series, vol. vi, 

 p. 36, fig. 3), but differs from it in the larger striae at sub-regular intervals, between the 

 groups of smaller, as well as in its greater size." He adds, also, that he has seen and 

 made drawings of a large number of specimens in private collections of persons at or near 

 Looe, although there is but one poor specimen in the Cambridge Museum, and is therefore 

 better prepared to decide on the character of the species than he should otherwise have 

 been. I have never seen any specimen with the shell preserved, so that the above 

 description is principally taken from that published by Professor M'Coy ; but a fragment 

 of a specimen, closely agreeing with Professor M'Coy's species, was figured by Roemer in 

 the same year under the name of 0. spat/tutala. The search for better material, with 

 reference to both M'Coy's and Roemer's species, will be very desirable. 



