GLYPHIOCERAS (BEYRICHOCERAS) DAVISI. 187 



much crushed or are merely impressions on the surface of pieces of shale occurring 

 in the Millstone Grit. No specimen can there be found so well preserved as repre- 

 sented in Salter's figure, and we have not seen the suture-line in any of these 

 examples. There are two forms : one with a rather open umbilicus exposing the 

 edges of the inner whorls, on which, as well as on the inner edge of the outer 

 whorl, the fine ornaments of the test are accompanied by small folds ; the other 

 with a much finer ornamentation, and a smaller and infundibuliform umbilicus. 

 The specimens in the National Collection agree with the latter. Shell attaining a 

 diameter of 56 mm." The specimens in the British Museum are from Halifax, 

 Yorkshire. 



Dimensions. 



Specimen from Caher Lane in the Dublin 



Mvis. Sci. and Art (Geol. Surv. 



Coll., No. 2208 C). 



Diameter of shell (approximately) . . 28 mm. 



,, umbilicus . . . . G ,, 



Height of outer whorl . . . . 14 ,, 



Affinities. — On the whole this species seems to be most nearly allied to 

 Glyphioceras (Beyrichoceras) reticulatum, but the ornamentation in the latter is 

 much coarser than it is in 67. hi 7 i injur, though, as remarked in the description of 

 G. (B.) David, it is of a similar character. The umbilicus is smaller than that of 

 the specimens described in the ' Catalogue of Fossil Cephalopoda, British Museum,' 

 p. 193, but this may be only an individual variation. 



Salter's figure (loc. cit.) has all the appearance of being a "restoration," and 

 there is apparently no individual specimen in the Jermyn Street Museum which 

 can be recognised as the original of it. The description given by Salter has, how- 

 ever, sufficed to distinguish the species, the " exaggerated processes on the edge of 

 the mouth " causing the " double concentric furrow near the periphery," making it 

 easily recognisable. This feature in it is seen in a milder form in the larger of 

 Phillips's figures of G. reticulatum (' Geol. Yorks,' ii, pi. xix, fig. 27). It is to be 

 observed that there are no constrictions on the shell in the present species. 



Localities. — Caher Lane (No. 2208 C), and Rathcahill (No. 3429 C), near 

 Abbeyfield, county of Limerick. 



Glyphioceras (Beyrichoceras) Davisi ? A. II. Foord and G. C. Crick Plate 



XLIX, fig. 4. 



1897. Glyphioceras Davisi, A. H. Foord and G. C. Crick. Cat. Foss. Ceph. 



British Museum, pt. 3, p. 198, figs. 95 a — c. 



Description. — Shell somewhat inflated, umbilicated, greatest thickness at the edge 

 of the umbilicus ; height of outer whorl about one-half of the diameter of the shell. 



28 



