174 CARBONIFEROUS CEPHALOPODA OF IRELAND. 



its height by the preceding whorl; sides somewhat flattened, peripheral area 

 very distinctly flattened in the young shell with a fairly well-marked rounded 

 margin. 



Body-chamber not seen. The suture-line is described but imperfectly figured 

 by M'Coy (loc. cit.) ; it is, however, figured by de Koninck (loc. cit., p. 99). Test 

 ornamented with fine transverse lines of sigmoidal form crossed by faint longi- 

 tudinal ridges both upon the sides and the peripheral area. A series of very 

 narrow and shallow constrictions are developed, about ten to a whorl ; these pro- 

 ceed from the region of the umbilicus with a slight, backwardly directed curve and 

 cross the peripheral area, making upon it a broad, backwardly directed sinus and a 

 well-marked angle at its margin on each side (PI. XL VI, fig. ha). 



Dimension*. 



Young shell from Ballinacarriga in 



the Dublin Museum of Science 



and Art (Geological Survey 



Collection). (No. 255.) 



Diameter of shell .... 35*0 mm. 



,, umbilicus . . . 1O0 ,, 



Height of outer whorl . . . 15*5 „ 



,, above preceding whorl . . . 8*0 ,, 



Thickness at umbilical margin . . . 22-5 „ 



Affinities. — This species is distinguished from G. Browni, M'Coy (p. 175), by its 

 smaller umbilicus, more inflated form, and by its ornamentation. It agrees well in 

 respect to the latter feature with de Koninck's specimens as figured by him (loc. 

 cit.), though the umbilicus in the Irish specimens is a little smaller. M'Coy gives 

 only one figure of this species, a lateral view, and therefore the peripheral flatten- 

 ing so well marked in the specimen from Ballinacarriga (PL XLVI, fig. 5) is not 

 exhibited. The present species differs both in sutural characters and in ornamenta- 

 tion, as well as in the flattening of the periphery, from G. (B.) sphaericum. 



Remarks.— A specimen (PI. XLVI, fig. 3) from Kilmallock (county of 

 Limerick), contained in the " Griffith Collection," has the name of this species 

 written upon the tablet on which it is mounted, and it has been doubtfully referred 

 to M'Coy's type (loc. cit.), but if it be this M'Coy's figure is inaccurate, as the 

 umbilicus is represented as being much larger than it is in the specimen. The 

 figure also shows a part of the suture-line upon the last whorl, whereas no trace of 

 I his is seen upon the specimen. On the whole, however, it appears to belong to 

 the species to which it has been assigned, viz. G. (/>'.) sphaeroidale. 



Localities. — Ballyrichard, county of Cork (No. 47G7 — Dublin Museum of 

 Science and Art, Geological Survey Collection); Kilmallock and Ballinacarriga, 

 comity of Limerick. 



