188 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



Whorls probably five or six ; inclusion almost complete ; umbilicus about one-tliird 

 of the diameter of the shell in width, the sides steep, the margin subangular, 

 exposing the edges of the inner wlioids ; inner area well defined, rather narrow, 

 almost at right angles to the plane of symmetry. Test thin, the ornamentation 

 consisting of regular, distinctly crenulated transverse strife, which bifurcate shortly 

 after leaving the margin of the umbilicus ; these take a nearly straight course for 

 a short distance, then bend backwards, then more strongly forwards. (The peri- 

 pheral area is not preserved.) Faint spiral lines are seen on the sides of the shell, 

 which nearer the periphery become as prominent as the transverse strijB, and 

 produce a reticulate structure. At about two-thirds of the distance across the 

 lateral area there is a distinct rounded spiral ridge, which on the side nearest to the 

 periphery merges in a depression in which the transverse stria? make their strongest 

 forward curvature. No constrictions are to be seen. The siiture-line is unknown. 



Affinities. — The evidence in favour of this species being identical with Glypliio- 

 ceras Davisi, Foord and Crick, is not quite conclnsive, I have therefore put a note 

 of interrogation after the name. The doubt arises from the absence of the suture- 

 line and other imperfections in the only specimen that has come to my notice. The 

 general character of the ornamentation, crenulated and bifurcating sti'iaj, is well 

 brought out in fig. 7 c, PL XLIX — an allied species. 



Bemarls. — This species forms one of a group which includes Glypliioceras 

 {Beyriclwceras) reticnlatmn, G. (7>.) suhreticulatum, and G. (7?.) Jnlinrjiie. In all 

 these the ornaments of the shell are strikingly similar in their character, — that is, 

 they consist of crenulated, transverse, often bifurcating striae, with more or less 

 strongly developed spiral striae crossing them, the latter always strongest in the 

 peripheral region. This species was found at Rathcahill associated in the same 

 beds with G. (/?.) roficulatum and G. (B.) pvlchelbim. 



Lociilify. — Rathcahill, near Abbeyfield (No. :]4<35 C-), and Foynes Island 

 (No. 8L5 C, pars), county of Limerick. 



Glypiiiooeras (BEYRicnocEKAs) coRDATUM, G. 0. Oriel: Plate XLVII, figs. 2 a — c. 



1890. Glyphioceras cordatum, G. C. Grid-. Auu. Mag. Nat. Hist., .ser. 7, 



vol. iii, p. 445, fig. 10. 



Descrifption. — Shell discoidal, rather inflated, lenticular, narrowly and deeply 

 umbilicated ; greatest thickness at a short distance from the umbilical margin, a 

 little more than one-half of the diameter of the shell ; height of outer whoi'l a little 

 less than one-half of that diameter. Whorls probably not less than four, but the 

 exact niunber cannot be stated owing to the outer one being imperfect. Inclusion 



