G. C. Crich — Pericyclus fasciculatus, M'Coy. 31 



to denote the position of the umbilical margin, and not that of the 

 ^line of involution,' or, as it is generally termed, the 'suture of the 

 shell.' 



Besides four specimens from Irish localities — two from Ireland, 

 but locality uncertain ; one from Limerick ; and one from Kildare — 

 the Museum of Practical Geology contains two English examples, 

 one being the specimen from Beeston Tor, 1 mile east of Grindon, in 

 North Staffordshire, already referred to, and the other from near 

 Matlock, in Derbyshire.^ 



The Beeston Tor specimen [No. 8860] is a small natural internal 

 cast bearing portions of the test in a very eroded condition. Its 

 dimensions are : — diameter of shell, 20 mm. ; radius, 12 mm. ; width 

 of umbilicus, about 7 mm. ; height of outer whorl, &-5 mm. ; thick- 

 ness of outer whorl, 16 mm.; height of the outer whorl above pre- 

 ceding, (?). There are about 30 ribs in the outer whorl, the last 

 half- whorl bearing 14. The specimen does not appear to be at all 

 crushed, but, as will be seen from its dimensions, it is relatively 

 thicker than any of the other examples. The suture-lines are not 

 shown. 



The example from near Matlock [No. 6696] is also a natural 

 internal cast ; besides the outer whorl, which is a little imperfect on 

 one side, about a quarter of the penultimate whorl is displayed, the 

 rest of the inner whorls being probably present, though occluded by 

 matrix. Its dimensions are: — diameter of shell, 32 ram. ; radius, 

 18 mm. ; width of umbilicus, 12 mm. ; height of outer whorl, 12 mm.; 

 thickness of outer whorl, 21mm.; height of outer whorl above 

 preceding, about 9 mm. There are 34: ribs in the outer whorl. 

 A little less than one-half of the outer whorl is occupied by the 

 body-chamber ; several suture-lines are well displayed ; the last is 

 represented in the accompanying figure. This specimen is relatively 



It 



Fig. 3. — Suture-liue of Pericyclus fasciculatm. Drawn of the natural size from 

 the last septum of an example (at a radius of 13'5 mm.) in the Museum of 

 Practical Geology . [No. 6696] from the Carboniferous Limestone, near 

 Matlock, Derbyshire. 



thinner than the Beeston example, for at a radius equal to the 

 greatest radius of that specimen this shell is only 13 mm. thick. 



Through the kindness of Dr. Wheelton Hind I have been able to 

 examine two examples in his collection that came from Bradbourne, 

 about 2 miles north of Kniveton, Derbyshire. Both are internal casts. 

 One is a fairly well preserved cast of the outer whorl, with the inner 

 whorls present, although broken on one side and obscured by matrix 

 on the other ; it has the following dimensions : — diameter, 34-5 mm. ; 

 radius, 20 mm.; width of umbilicus, 16-5 mm. ; height of outer 

 whorl, 11-0 mm. ; thickness of outer whorl, 21-5 mm. ; height of 

 cuter whorl above preceding whorl, 9 mm. About five-sixths of the 



1 My best thanks are due to Mr. E. T. Newton, F.R.S., for the facilities given me 

 to examine these fossils. 



