AGNOSTUS fNTEGER. L9 



1872. Agnostus cMibrensis, Hicks, Quart. Journ. Geol. Sue, w>l. xxviii, pi. v, fig. 1. (No1 Eicks, 



Quart. Journ. Geol. So.'., vol. xxvii | 1871 ), p. 400, pi. xvi, figs. 1 I and 12.) 

 1895. Agnostus integer, Pompeckj, Jahrb. It. k. geol. Reicks., vol. \lv, \>. 521. 

 1895. Agnosias integer, var. spinosa, Pompeckj, ibid., p. 522, pi. xvi, fig. t>a, b. 



Head subquadrate, somewhat longer than broad, with a narrow margin. 

 Glabella bilobed, anterior lobe small, broad, rounded in front; posterior lobe 

 somewhat wider than the anterior lobe, slightly constrieted in the middle, with a 

 small median tuberele; basal lobes small. Cheeks nearly equal in width throughout, 

 eontiuent in front of the glabella, rugose, marked by irregular furrows. 



Thorax : lateral nodules of axis nearly as large as the central portion. 



Tail quadrate, with a broad margin which widens greatly posteriorly, and is 

 produced into a very short spine at each side. Axis wide, somewhat contracted 

 at about one third of its length from the anterior margin ; divided by two furrows 

 on each side, which do not quite reach the middle; with a median keel; terminates 

 in a blunt point which does not quite reach the posterior margin. Lateral lobes 

 narrow, reduced behind the axis, where the two lobes unite, to a mere strip. The 

 margin is narrow in front, widens posteriorly, and is produced into two very short 

 lateral spines. 



Head- and tail-shields about 3 — 4 mm. long and wide. 



A. integer presents some resemblance to A.fallax, Linrsn. ; but in J. fallax the 

 glabella is smaller and the posterior lobe is little, if at all, wider than the anterior 

 lobe ; the axis of the tail is shorter and the divisions upon it are less distinct. 

 A.fallax, moreover, appears to be smooth and without the rugosities characteristic 

 of A. integer, and the margin of the head is wider than in the latter species. 



Both Beyrich and Corda represent the tail of this species with lateral spines, 

 but Barrande asserts that these do not exist. Pompeckj states that many of the 

 specimens are not spined and that the tail is merely sharply angular, but in some 

 examples from "Pod hruskou," near Tejrovic, and also in some from Jinec, he 

 finds that the angles are produced into short teeth, and to this form he gives the 

 name of var. spinosa. Pompeckj's figure also agrees with the Welsh specimen in 

 the fact that the axis does not quite reach the margin of the tail. 



Synonymy. — The specimen here described is that which was figured by Micks 

 in 1872 as Agnostus cambrensis, but it is quite different from the form which he had 

 already described under that name in 1871, and which belongs to the group of 

 Agnostus rex. The resemblance to Agnostus integer, as described and figured by 

 Barrande, is complete, except for the fact that the margin of the tail bears short 

 spines and that the axis does not quite reach to the posterior margin. In the 

 latter respect the specimen agrees with the younger forms figured by Barrande. 



Types. — The original of llicks's figure of "J. cambrensis" in 'Quart. Journ. 

 Geol. Soc.,' vol. xxviii, pi. v, fig. 1, is in the Sedgwick Museum. 



Horizon <ut<l Locality.— Menevi&n: Porth-y-rhaw, St. David's. 



