﻿2SS ARTHRODIRA. 



P. 685. Ten specimens exhibiting plates of the head and trunk. 



Egerton Coll. 



49185-86. Two specimens of the head and armoured trunk, in 

 counterpart. Broad teeth are shown in the mandible of 

 both specimens. Purchased, 1876. 



21574, a, b. Three examples of the dermal plates of the head and 

 trunk, the second and third being preserved in counter- 

 part. In the first specimen the median occipital of the 

 cranial shield exhibits the characteristic median elevation, 

 and the "posterior ethmoidal" (pineal) shows a distinct 

 cast of the large central pit on its inferior aspect. 



Presented by Norman McLeod, Esq., 1847. 



20792 a-b. Fine example of the dermal plates of the head and 

 trunk, preserved in counterpart. The maxillary or sub- 

 orbital elements are displaced, and the supposed operculum 

 is observed immediately behind on each side. The tuber- 

 cular ornament is very coarse ; and behind the median 

 dorsal plate there occurs one of the pelvic basipterygia. 



Presented by Col. Sir Proby T. Cautley, K.C.B., 

 and — Gordon, Esq., 1847. 



P> 5960-1. Two specimens showing various dermal plates, the first 

 including the mandibular rami with teeth. 



Purchased, 1889. 



P. 685 C Median dorsal plate, broken to exhibit the extent of the 

 inner longitudinal keel. Egerton Coll. 



P. 5060. Median dorsal plate. Presented by J. E. Lee, Esq., 1885. 



P. 6073. Median dorsal plate with imperfect portions of other 

 elements. Presented by F. Harford, Esq., 1889. 



P. 3225. Crushed median dorsal plate. Enniskillen Coll. 



(vi.) Tynet Burn. 



43617. Imperfect individual wanting the posterior half of the 

 caudal region, lateral aspect, in counterpart. The dermal 

 plates of the head and trunk are much broken, but several 

 characteristic elements are exhibited ; while the region 

 immediately behind the armour is especially well preserved. 

 The latter is shown, of the natural size, in PI. VII. fig. 2, 

 and the parts are lettered in accordance with the following 

 description. Emerging from beneath the median dorsal 



