36 SYNOPSIS OF THE CHARACTERS OF THE 



EuOMPHAxus (Phanerotinus) CRISTATUS. Phil. SP. 



Euomphalus cristatus. Phil. Geol. York. — Phanerotinus cristatus. Sow. Min. Con. 



An imperfect fragment of this singular shell has been obtained. It is easily known by its disjoined whorls, 

 and large, dentated, compressed, dorsal crest. The specimen in Mr. Griffith's Collection must have been about 

 six inches in diameter. 



EUOMPHALUS CROTALOSTOMUS. MCoy. (PL VII. fig. 4). 



Sp. Ch. — Discoid, depressed; spire slightly raised, of five whorls ; a depressed or flattened space on the 

 top of each whorl, bounded by an obscure keel ; back flattened, convex ; base flattened ; imibilicus very large ; 

 mouth dilated ; surface with transverse irregular lines of growth. 



This species occasionally reaches a foot in diameter ; the spire is very shghtly raised ; the mouth, in old in- 

 dividuals, is dilated, bell-shaped (whence the specific name), the remains of the expanded margins giving a 

 peculiarly rugged aspect to the last whorl. 



EuOMPHALUS ELONGATUS. M'Coy. (PL III. fig. 12). 



S}). Ch. — Elongate, conic, spire acute, nearly equalling in height the diameter of the base; of five gradu- 

 ally increasing whorls ; upper half of the volutions plane, lower half convex ; the two portions separated by an 

 obtusely rounded keel ; surface smooth. 



This species is distinguished from the E. acuhis by its gradually increasing whorls, and from the E.penta- 

 gonalis and Natica tabulata, as well as E. acutus, by the greater length andacuteness of the spire; it is also a 

 much smaller species than any of them. Length about three and a half lines, width of basal whorl two and a 

 half lines. 



EuOMPHALUS MARGINATUS. MCoy. (PL V. fig. 21). 



Sp. Ch. — Discoid, spire depressed; whorls convex below, flat or slightly concave above; upper surface of 

 the whorls bounded exteriorly or dorsally by an obtuse keel, which separates it from the back, and interiorly or 

 ventrally by a narrow tumid border. 



The volutions are four or five in number, of the same form as the E. pentangulatus, from which the tumid, 

 prominent, inner margin of the whorls distinguishes it ; it is also more strongly striated across. Diameter two 

 inches three lines, thickness of last whorl seven lines. 



EuOMPHALUS NEGLECTUS. M'Coy. (PL V. fig. 23). 



Sp. Ch. — Spire very much depressed, formed of three rounded volutions; umbilicus wide, rounded, sur- 

 face smooth. 



This shell has been figured by Professor Phillips, in PI. XV. fig. 31, of the Geology of Yorkshire, where, 

 however, it is not described, being passed over in the explanation of the plates as a probable variety of the C. 

 rotundatits; from that species, however, it is at once distinguised by the very small number of whorls, and the 

 flatness of the spire, which hardly rises above the last volution ; I have seen a considerable number of specimens 

 from different localities in Ireland, and in all I have seen, the characters were constant. Diameter three lines, 

 thickness of last volution one line. 



