168 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



pressed than others. The flattening of the periphery and the compressed form of 

 the shell are, however, the distinguishing marks of the species, making due allow- 

 ance for local variability. 



Taking the present species as the typical form, the following species added to it 

 make up the group of G. (B.) truncatum : — G. (B.) subtruncatum, G. (B.) occidentale, 

 G. (B.) difficile, G. (if.) subquadratum. 



In the supplementary plate (PI. XLIX, fig. 14) will be seen the suture-line of 

 the present species taken at a point remote from the body-chamber, and therefore 

 probably representing the chambers at their normal distance apart. Fig. 2 c of 

 PI. XLIV, on the other hand, depicts the last three septa, which, as is so com- 

 monly the case, are somewhat nearer together. The peripheral lobe in this figure 

 was defective in the specimen, and it is represented much too narrow. Fig. 14 on 

 PI. XLIX is taken from a specimen about 90 mm. in diameter belonging to the 

 Museum of the Royal College of Science for Ireland, Dublin, kindly lent to the 

 author by Professor Grenville A. J. Cole, M.R.I. A., F.G.S. 



Localities. — Drumscra (Drumquin), county of Tyrone; St. Doulagh's, county of 

 Dublin; Clane, county of Kildare; Ballyduff (Dungarvan), county of Waterford ; 

 Little Island, Tankardstown (Kildorrery), and Midleton, county of Cork; Lisna- 

 kerry, Nantenan, Ballycahane, and Kilmacat, county of Limerick. 



GrLYPHIOCERAS (BEyRlOHOCEEAS) SUBTRUNCATUM, sp. nOV. Plate XLV, figs. 3(1 — (/, 



4 a — c. 



Description. — Shell of medium size, discoid, somewhat compressed, composed of 

 from six to seven whorls (?) ; the greatest thickness at about one-fourth of the height 

 of the whorl from the edge of the umbilicus, about three-sevenths of the diameter 

 of the shell; height of outer whorl about four-sevenths of the diameter of the shell. 

 Inclusion of the whorls nearly complete ; umbilicus small in the young and 

 adolescent stage of growth, but proportionately larger in the adult. Whorl 

 subquadrangular in section, about one-third higher than wide, indented to about 

 one-third of its height by the preceding whorl. Periphery about one-third of the 

 height of the outer whorl in width, more or less perceptibly flattened ; umbilical 

 zone indistinct, gently convex, merging in the sides of the shell. Body-chamber 

 occupying rather more than an entire volution ; aperture, so far as may be judged 

 by the lines of growth, with a prominent crest in young individuals (PI. XLV, 

 fig. 4 n), which becomes somewhat less strongly marked in older ones. Chambers 

 moderately deep, apparently sixteen or seventeen to a whorl. Suture-line as in 

 PL XLV, fig. 3 d. 



Test thin for the most part, but becoming thicker in the umbilical region, having 



