PERICYCLUS FASCICULATUS. 135 



marked feature in tlie ornamentation of P. faseiculatus. The ril)s are almost 

 direct upon the sides of the shell, and form a broad and shallow sinus upon the 

 periphery. 



Dimensions. 



Specimen in Museum, Trinity 

 College, Dublin. 



Diameter of shell (elliptical by rock pressure) . 78 mm. 



„ umbilicus (suture to suture of the longer 



diameter) . . . .36,, 



Diameter of umbilicus (of the shorter diameter) . 30 ,, 



Thickness at uml)ilical marg-in . . . 36 „ 



&' 



Afinities. — A comparison between this species and 1\ faseiculatus is made under 

 the description of the latter (see below). From P. pUcatills, de Kon., it is easily 

 distinguished by its more compressed shape, its wider and much shallower 

 umbilicus, and its much coarser ribbing. 



Bemavlcs. — Only three specimens of this species are known to me, one of which 

 is the type specimen in the British Museum (" Sowerby Collection "), unfortunately 

 very imperfect (PI. XXXVIII, fig. 5) ; another and much better specimen of about 

 the same size contained in the museum of Trinity College, Dublin ; and the third 

 a young shell (cast) belonging to Mr. Joseph Wright, F.G.S., of Belfast. All 

 three were obtained in the neighbourhood of Cork, and all are distorted in a similar 

 manner. The pressure causing the distortion has operated from above in a 

 direction oblique to the plane of the umbilicus such that the peripheral area, 

 instead of being at right angles to that plane, as it Avould be normally, presents an 

 angle of nearly 45° to it, as the result of this severe crushing. 



The Trinity College specimen, mentioned above, was kindly lent to me by 

 Professor J. Joly, F.R.S. 



Localities. — " Blackrock range, south-east of Cork " (Sowerby's type in the 

 British Museum) ; " Cork " (Trinity College specimen) ; " near Cork " (j\Ir. 

 Wright's specimen, formerly in the collection of Dr. Haines, of Cork). 



Pericyclus fasciculatus, F. M'Coi/, sp. Plate XXXVII, figs. 2 — 6. 



1844. Nautilus (Temnocheilus) purcatus, F. M'Coy. Synops. Carb. Foss. 



Ireland, p. 21, pi. iv, fig. 13. 

 — GoNiATiTES FASCICULATUS, F. M'Coij. Syiiops. Carl). Foss. Ireland, p. 13, 



pi. ii, fig. 8. 

 1850. Aganides subfurcatus, A. d'Orbigny. Prod, de Palt'ont. stratigr., vol. i, 



p. 115. 



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