342 BRITISH SILURIAN BRACHIOPODA. 



Obolus pltjmbeus, var. plicata, Hicks. PI. L, fig. 22. 



After a lengthened study and comparison of a smaller form, sent to me by Mr. Hicks, 

 with the designation of Oholella plicata, which occurs sparingly in the " Lower Arenig or 

 Skiddaw Group" at Tremanhire and Ramsay Hand, near St. David's, in South Wales, I 

 could not divest myself of the idea that this last was nothing more than a small variety of 

 the typical form which occurs in the " Upper Arenig'' or " Lower Llandeilo" rocks of North 

 Wales. In external shape this variety ^'plicata" is somewhat transversely oval, obtusely 

 acuminated posteriorly, broadly rounded anteriorly ; the largest example I have been able 

 to examine did not exceed four lines in length, by five in breadth. The valves are slightly 

 convex, and marked by numerous fine, thread-like, radiating, bifurcating striae. No 

 sufficiently perfect interior having been discovered, I cannot attempt to describe its in- 

 ternal characters. I must also here observe that Mr. Hicks admits the possibility of his 

 Obolella plicata being a small variety of Obolus {?) plumb eus. 



Genus — Kutorgina, Billings, 1861. 



The characters of this genus (?) have not yet been fully discovered or described ; but 

 the exterior of the shell presents some remarkable peculiarities. 



Kutorgina cingulata, Billings. PI. L, fig. 25. 



KuTOKGiNA CINGULATA, Billings. Geol. Surv. Canada, Pal. Foss., vol. i, pp. 8, 9, 10, 



1865. 

 Obolella (?) Phillipsii {Soil), Bav. Supra, p. 62, pi. iv, figs. 17 — 19, 1866. 

 'KuioiiGm A. cmGXSjjKTK {Billings), Dav. Geol. Mag., vol. v, p. 312, pi. xvi, fig. 10, 



1868. 



When preparing the first portion of this 'Silurian Monograph/ I felt very uncertain 

 as to the genus and species to which the so-termed Obolella PJiillipsH should be referred. 

 Since then, thanks to the kindness of Mr. Billings, I have been able to compare his 

 Canadian type of Kuforgina cingulata with a similar-sized example of Obolella PJdllipsii 

 kindly presented to me by the Rev. W. S. Symonds. I was able to show these specimens 

 to Dr. Holl, and he at once agreed with me that his Ob. PJiillipsii and the American 

 shell belonged to the same species. Neither, however, were at all referable to the genus 

 Obolella ; their long, straight, hinge-line precluding such a possibility. The term Obolella 



