■30 G. C. Crick — Pericyclus fasckulatuSf M'Coy. 



recorded ; this was from the Carboniferous Limestone of Clane, 

 CO. Kildare, Ireland, and was presented to the Collection by Dr. A. H. 

 Foord. It was figured (under the name Pericyclus furcatus) in the 

 " Catalogue of the Fossil Cephalopoda in the British Museum 

 (Natural History)," pt. iii, p. 150, fig. 71, and has been re-figured, 

 (under the name Pericyclus fascicnlatus) by Dr. Foord in his 

 " Monograph on the Carboniferous Cephalopoda of Ireland," pt. iv 

 (1901), pi. xxxvii, figs. 2«, h, its suture-line being given in Fig. 1 

 accompanying this paper. Its dimensions are : — diameter of shell, 

 51 mm. ; radius, 29'5 mm. ; width of umbilicus, 17 mm. ; height of 

 outer whorl, 20 mm. ; thickness of outer whorl, 35 mm. ; height of 

 outer whorl above preceding whorl, 17 mm. As nearly as can be 

 ascertained the outer whorl bears 34 ribs. It lacks the test and 

 agrees with M'Coy's type of furcatus. Besides this, the National 

 Collection contains two examples [N^o. C. 5773], 3i and 17'5mm. 

 in diameter respectively, like M'Coy's type of fascicnlatus, but 

 unfortunately the locality whence they were obtained has not been 

 recorded. 



In 1901, however, a well-presei*ved but imperfect example from 

 the Carboniferous Limestone of Kniveton, 2 miles north-east of 

 Ashbourne, Derbyshire, was presented to the British Museum 

 [No. C. 7961] by the Rev. F. St. John Thackeray, M.A., F.G.S. 

 It is a natural internal cast, and consists of the inner whorls up to 

 a diameter of about 22 mm. that are entirely septate, and of about 

 one-half of the succeeding whorl, which is about 40 mm, in diameter, 

 and belongs to the body-chamber. At its greatest diameter, 40 mm., 

 the other dimensions appear to have been : — radius, 23 mm. ; width 

 of umbilicus, 14 mm. ; height of outer whorl, 14 mm. ; thickness of 

 outer whorl, 27 mm. There are eighteen or nineteen ribs in the last 

 half-whorl. At a position on the inner whorls where the shell has 

 a radius of 9 mm. the suture-line is displayed on both the peripheral 

 area and the umbilical margin, and somewhat less clearly on the inner 

 area or umbilical zone of the whorl. It is represented in the 

 accompanying figure. Compared with " the suture-lines of a small 



WYVv 



Fig. 2. — Sutiu-e-liue of Fcricijdus fascicnlatus. Drawn of the natural size from 

 a specimen (where radius is 9 mm.) in the British Museum [No. C. 7961] 

 from the Carboniferous Limestone, Kniveton, 2 miles N.E. of Ashbourne, 

 Derbyshire. 



specimen where the diameter of the shell is about 30 mm.," given by 

 Dr. Foord {op. cit., pi. xxxvii, fig. 6), we note in the present specimen 

 that where the radius is onljf about 10 mm. and the diameter therefore 

 not more than about 18 mm., the sides of the external lobe are more 

 nearly parallel, the external saddle is rounder, the lateral lobe is even 

 at this diameter distinctly pointed, whilst a pointed, acutely V-shaped 

 lobe is present on the inner area or umbilical zone of the whorl. No 

 such lobe as the last-mentioned is indicated in Dr. Foord's figure, but 

 it may be that the short line at each end of the suture-line is intended 



