﻿293 



ARTHRODIRA. 



38032 a. Portion of shield ; Heigbtington. Purchased, 1864. 



38032 b. Fragment with impression of tubercular ornament, 

 exhibiting a tendency towards a concentric arrangement, 

 and partly shown, of the natural size, in PI. VIII. fig. 7 ; 

 Heightington. Purchased, 1864. 



37388 b. Imperfect flat plate, shown, of the natural size, in PI. VIII. 

 fig. 8, and probably referable to the ventral armature of 

 the trunk. Two of the four borders of the plate are 

 apparently thicker than the others, are unbroken, and 

 meet in a wide, rounded angle ; the tubercles are arranged 

 in series concentric with these borders for some distance 

 towards the centre of the plate, and gradually decrease in 

 size until they become very small inwards. 



37388 C, 38032 c. Two nearly similar plates ; Heightington. 



Purchased, 1864. 



The following is a bilaterally-symmetrical ridge-plate, resembling 

 that assigned to Zenaspis by Lankester, ojj. cit. pi. viii. figs. 2, 3 ; 

 reasoning from the shape of the plate and the character of its orna- 

 mentation, it may well be the dorsal shield of the trunk of Phlyc- 

 tcenasj>is anglica. 



38032 d. Internal cast of shield, with fragments of the bony tissue 

 and its characteristic .ornamentation preserved at what 

 appears to be the hinder extremity ; Heigh tiogton. There 

 are remains of an inner longitudinal keel, apparently re- 

 sembling that of the median dorsal plate in Coccosteus. 



Purchased, 1864. 



The following specimens from the Lower Old Red Sandstone of 

 Herefordshire may also pertain to Coccosteidae related to Phlyctcen- 

 asjpiS) but their determination is quite uncertain : — 



P. 194. An oval plate, exposed from the inner aspect, truncated 

 at one extremity, measuring 0*095 in length and 0*063 

 in maximum breadth. There is a longitudinal median 

 elevation in one half of the shield, and an impression 

 of part of the outer aspect shows that it was coarsely 

 tuberculated. Weaver-Jones Coll. 



P. 5274. Two small ridge-scutes, probably of an imbricating series, 

 and externally ornamented with large tubercles ; Cradley. 

 One specimen is shown, of the natural size, in PL VIII. 

 fig. 9. Purchased, 1885. 



