﻿OSTEOLKPlDiE. , 385 



scales and head-bones apparently thinner than in the last-named 

 species. 



Though regarded by Young as the type of a distinct genus, 

 llhomboptychius, on account of the characters of the scales and 

 teeth, the specimens mentioned below prove tbat no sufficient basis 

 for the generic separation of this species from Megalichthys can yet 

 be established. 



Form. 4" Loc. Coal-Measures : South Scotland and North Stafford- 

 shire. 



37320-21. Two slabs of shale exhibiting various bones and scales ; 

 Airdrie, Lanarkshire. The first specimen, which is to be 

 regarded as the type, shows the left mandibular ramus 

 and other portions of the jaws with teeth, the oral aspect 

 of some of these bones being covered with numerous 

 small, closely-arranged dental tubercles, as described by 

 Young ; the greater portion of the operculum is seen 

 from the inner aspect, and several scales are preserved, 

 showing not only fragments of the superficial ganoine- 

 layer, but also, in some instances, a well-marked median 

 rib on the inner side ; a few of the characteristic slender 

 ring-vertebrae also occur. The second specimen shows 

 the pair of jugular plates and portions of jaws, with 

 teeth, from the inner aspect ; the larger teeth are trans- 

 versely banded, and the external aspect of the bones is 

 covered with ganoine. Purchased, 1863. 



P. 3324. Jugular plate; Gubbin Ironstone Shale, Shelton, North 

 Staffordshire. Enniskillen Coll. 



37974-75. Two slabs with miscellaneous remains ; Airdrie. 



Purchased, 1863. 



P. 3303. Group of head-bones ; Carluke. Enniskillen Coll. 



P. 4465. Small slab with miscellaneous remains ; Carluke. 



Enniskillen Coll. 



P. 4802. Greater portion of right maxilla with teeth ; Palace Craig 



Ironstone, Airdrie. Armstrong Coll., transferred from 



Mus. Science Sf Art, Edinburgh, 1884. 



39248. Portion of maxilla ; Airdrie. Purchased, 1865. 



37973, 38010. Portions of two large mandibular rami showing the 

 bases of teeth, one associated with detached scales ; 

 Airdrie. Purchased, 1863-64. 



PAET II. 2 c 



