450 Mv. G. C. ('rick on some 



Dimensions. 



(i.) (ii.) 



Piameter of shell . . 83 mm. (100) 70-5 mm. (100) TOu mm. (100) 



AVidtli of umbilicus 



(at suture of shell) 20 „ (24-0) ? 14 „ (lO'S) 



^Vidth of umbilicus 



(atitsmar^n).. 23-5 „ (28-3) 17-5 mm. {24-8) 17 „ (24-1) 



Ileitrht of outer 

 whorl 36 „ (433) 31-0 „ (43-9) 31-5 „ (44G) 



Ditto above pre- 

 ceding whorl ..25 „ (30-1) ? 21 „ (29-7) 



Thickness of outer 

 whorl 47 „ (o6-6) 43 mm. (GO-9) 39-5 „ (56) 



Bemorl's. The type specimen of this species — tlie example 

 upon which the diagnosis given above has been chiefly based — 

 is in the collection of the Museum of Science and Art, 

 Dublin. The specimen is labelled " Kildare," and does not 

 appear to be at all crushed or distorted. The whole of the 

 outer whorl appears to be occupied by the body-chamber, so 

 that I have not been able to make out the form of the 

 suture-line. With some doubt I also refer to this species 

 an example in the British Museum collection (no. C. 294) 

 from the Carboniferous Limestone of Rathkeale, Co. Limerick ; 

 but, as will be seen from its dimensions given above (ii.), it 

 is somewhat more compressed than the type specimen, but 

 some of this compression may have been produced during 

 fossilization. De Koninck recognized three divisions of the 

 Carboniferous Limestone in L'eland — upper, middle, and 

 lower; he referred the Hmestone at Ratlikeale to the middle 

 division, whilst that at Kildare he placed in the upper 

 division. 



Affinities and Differences. This species differs from Gly. 

 f<2)hcericum, Martin, sp.*, in being less inflated and more 

 umbilicated. Compared with Gly. crenistria, Phillips, sp.f, 

 it is more compressed, its ornaments are not crenulated, and 

 they form a much deeper liyponomic sinus. Its transverse 

 ornaments (or growth-Hnes), larger uml ihcus, and more in- 

 flated shell at once distinguish tliis species from Oly. striatumX, 

 J. Sowerby, sp. 



* ConchylioUthus Nmttilites sphcerkus, W. Martin, Petrif. Derb. 1809, 

 p. 16, pi. vii. figs. 3, 4, & 5. 



t Goniatites c7-enist}-ia, J.Phillips, Geol. Yorks. ]it. ii. 1836, p. 234, 

 pi. xix. tigs. 7, 8, 9. 



X Ammonites stn'atus, J. Sowerby, Min. Conch, vol. i. p. llo (1814), 

 pi. liii. tig. 1. 



