240 DEVONIAN FOSSILS. 



lateral lobe or medial saddle (sinus) as in the other allied forms ; 

 this flection forward to the umbilicus distinguishes this part very 

 strongly from C. Icevigata, which also has very much more nu- 

 merous whorls and larger umbilicus. I have much pleasure in 

 dedicating this species to Mr. Pattison of Launceston, to whose 

 labours in collecting, I believe, are due the discovery of nearly 

 all the British specimens of Clymenia. 



Rare in the Devonian limestone of S. Petherwin. 



[Col. University of Cambridge.) 



Cyrtoceras suhornatum (M^Coy). 



Sp. Char. Gradually arched, involute; section of the whorls a 

 regular transverse ellipse, the shortest axis in the plane of in- 

 volution ; tapering at the rate of 5 lines in 2 inches from a 

 diameter of 1 inch 5 lines ; periphery broadly arched, inner 

 face rather more convex; sides elliptically rounded, with an 

 obscure spiral ridge on each side along the most prominent 

 part, bearing a row of large obtuse conical tubercles, nearly 

 twice their diameter apart ; on each side of this principal row 

 of tubercles is a secondary obscure row, about half as far from 

 the principal ridge as the tubercles of it are from each other, 

 the outer of these rows most distinct, the inner nearly obsolete ; 

 these three sets of tubercles are connected by very obscure 

 transverse wrinkles, which do not extend beyond them across 

 the inner aspect, or the periphery ; entire surface crossed by 

 very minute, imbricating waving lines of growth having a very 

 obtusely angular backward sinus in the middle of the peri- 

 phery, all crossed by very faint longitudinal folds half a line 

 apart, never assuming the prominence of striae or ridges; 

 siphon close to the outer margin. Proportional length of 

 mouth as compared to the width ■^■^^. 



This beautiful species is most nearly allied in form, size, septa, 

 siphon and striation to the C. ornatum (Goldf.), as figured by 

 D'Archiac and DeVerneuil in the ' Geol. Trans.' vol. vi. t. 28. f. 5, 

 but is rather less rapidly curved, and is completely distinguished 

 by the two or three rows of tubercles being very small, and en- 

 tirely confined to the sides, leaving the broad periphery com- 

 pletely free of them. 



One fragment in the Devonian limestone of Plymouth. 



[Col. University of Cambridge.) 



