AGNOSTUS CYCLOPYGE. 27 



"Horizon and Locality. — Tremadoc: collected by Mr. R. Rhodes for the Geological 

 Survey from the Shineton Shales of Shropshire, in Shineton Brookatl8 — 20 chains 

 S.W. of Shineton Church and also in the stream, Mary's dingle, 1 1 chains W.S.W. 

 of Morell's Wood." 



2o. Agnostus cyclopyge, Tullberg. Plate TT, ligs. 21, 22. 



1868. Arjnnatiis ohtusus (pars), Belt, Gcol. Mag., vol. v, p. 10, pi. ii, figs. 15, 10 (tails only). 

 1880. Agnostus cychjpyge, Tullberg, Agnostus-arterna, p. 20, pi. ii, fig. 15 a, c. 



Head rounded, with a fairly wide margin. Glabella bilobed, but the furrow 

 separating the two lobes very faint ; the anterior lobe rounded in front ; the 

 posterior lobe slightly constricted towards the middle, the anterior corners swollen 

 into small nodules, and a median tubercle also present; basal lobes fairly large. 

 Cheeks nearly uniform in width throughout, separated in front of the glabella by 

 a deep groove. 



Tail somewhat quadrate, surrounded by a wide margin, which is produced into 

 short lateral spines at the posterior angles. The axis, so far as it is distinct from 

 the rest of the tail, is very short, about one third the total length, pentagonal in 

 shape, bounded laterally by two nearly parallel furrows and posteriorly by two 

 furrows which meet at a very obtuse angle and are produced somewhat beyond the 

 lateral furrows before they die out; at the angle where these furrows meet there is 

 a small tubercle or keel. The rest of the tail is uniformly smooth and but little 

 convex. 



Head- and tail-shields about 3 mm. long and 8 — 3*5 mm. wide. 



There is no species with which this form is likely to be confounded. The 

 characters of the tail are quite unique, and the glabella is unlike that of any other 

 British species. 



Belt's figure of A. ohtusus is very imperfect, but the specimen with his label 

 in his collection (now in the British Museum) shows that the tail is identical with 

 that of A. cyclopyge. On the same slab occur heads which are decidedly different 

 from the head of J. cyclopjge as figured by Tullberg, and it is apparently from 

 these that Belt has drawn his description of the head of A. obtusus. He even 

 figures a complete specimen with the head and thorax attached to the tail, but 

 unfortunately this specimen is not now to be found. In the Oxford Museum, how- 

 ever, there is a complete specimen from the Black Shales of Malvern ; and though 

 the head is not in a very good state of preservation, it is sufficient to show that it 

 agrees with Tullberg's description and not with Belt's. It appears best, therefore, 

 to restrict Belt's name J. obtusus to the heads which he described. It must, how- 

 ever, be admitted that the specimen in the Pelt collection would lead one to infer 

 that the heads and tails belong to the same species. 



