DEVONIAN FOSSILS. 235 



lines or imbrications of growth towards the margin. Length 

 of receiving valve 2~ inches, proportional length of entering 

 valve /^^y, width /^"q, depth of both valves y^^^^. Thickness of 

 shell in beak of receiving valve 3 lines, above the beak of 

 entering valve on one side 5 lines, on the other side 4 lines, 

 diminishing the cavity to 2 lines in diameter ; thickness of 

 shell about the middle of the sides of receiving and entering 

 valve 3 lines, diminishing to little more than 1 line along the 

 middle, and gradually thinning to the margins; length of 

 young specimens 9 lines, proportional length of entering 

 valve -^^Q, width -f-^^, depth of both valves -^q^-^ . 



The general narrow elongate form, and the oblique torsion of 

 the long, narrow, claw-like beak in this species, exactly reminds 

 us of the Uncites gryphus of Defrance, from which it is distin- 

 guished by the absence of the longitudinal sulcation. Having 

 first ascertained the true internal characters of that curious Eifel 

 fossil, it gave me great pleasure to recognise in our British rocks 

 a second species of this remarkable genus. I should have ima- 

 gined that the smaller of the two figures given in Sowerby's 

 * Mineral Conchology ' under the name of Terebratula porrecta 

 represented a young individual of this species, on account of the 

 narrow produced front, but as Mr. Sowerby himself has since 

 stated (G. T. 2 S. vol. v. expl. of t.56)that those figures represented 

 the String ocephalus Burtini, and as all writers seem to coincide in 

 that opinion, I have only to observe, that the present fossil, by 

 thfe complete absence of internal septa, and the external charac- 

 ters above enumerated, has no affinity whatever therewith. 



Not uncommon in the Devonian limestone of Newton Bushel, 

 Devonshire. 



{Col. University of Cambridge.) 



Orthis persarmentosa (M'Coy). 



Sp. Char. Transversely oblong, hinge-line nearly the length of 

 the shell, ends obtusely subtruncate, slightly rounded ; surface 

 covered with thick, rugged, rounded, flexuous^ radiating ridges, 

 about half their thickness apart (about five in three lines in the 

 middle of the shell at six lines from the beak), branching four 

 or five times between the beak and margin, counting about 

 130 at the margin of a large specimen, those towards the 

 sides straighter and finer than those in the middle. Average 

 width 3 inches ; length probably one-third of the width, but 

 cannot be stated accurately, owing to the distortion of all the 

 specimens. 



This species very closely resembles the 0. sarmentosa (M'Coy) 



