1866.] YOUNG CARBONIFEROFS GLYPTODIPTEKINES. 605 



growth lines are confined to the margin ; the oval boss is sub- 

 central. The outer surface of these scales is finely punctate, dense, 

 and semilustrous. 



The Andersonian Museum of Glasgow contains a large slab on 

 which are displayed the vertebral column and upper surface of the 

 cranium of this genus. About fifty vertebrae are seen, of which the 

 anterior are the shortest and broadest, the caudal being longer 

 and narrower. The cranium is flattened superiorly ; its surface is 

 tuberculated and traversed by mucous grooves, and hues which 

 seem to be the sutures of the coalesced bones. 



The cranial and facial portions occur as separate masses, the com- 

 ponents of each being intimately united. The facial portion, con- 

 sisting of the bones anterior to 'the frontals (those, namely, which 

 compose the muzzle), very closely resembles thsit of Megalichthys and 

 Diplopterus. Its crescentic anterior, or intermaxillary and vomerine, 

 portion bears within and close to either outer extremity a large tooth ; 

 and on either side of the middle line is a similarly socketted tooth. 

 The small marginal teeth are continuous with two curved rows of 

 equally small teeth which pass in front of the outer pair of tusks, 

 and curving to their inner side meet in the middle line at the ante- 

 rior part of the basilar bar, whose surface is closely set with fine 

 denticles. 



The cranial shield is sohd ; its elements, intimately united by 

 suture, correspond in number with those found in the cranial roof 

 of Megaliclitliys (Poiss. Foss. pi. 63). But the well-ossified ba- 

 silar region includes a massive basioccipital which projects be- 

 hind the vertical posterior wall of the cranium, and sometimes has 

 its length increased by the coalescence with it of at least the first 

 vertebral ring, whose neural processes remained distinct. The an- 

 terior part of the cranial is sometimes deficient, the sphenoidal (and 

 prootic ?) portion becoming detached. In a lateral view, the ascend- 

 ing alisphenoidal (?) plates and an incomplete interorbital osseous 

 septum are well seen. 



The lower boundary of the elongated orbital space is nowhere 

 preserved, the only surviving parts of the lateral surface of the head 

 being the large opercular plates and the maxillae. 



The maxilla is slender in front, and sends off near its truncated 

 extremity a strong process directed inwards and forwards, for 

 articulation, probably, with the prefrontal or ethmoidal region. It 

 gradually expands posteriorly, and bears on the greater part of its 

 inferior margin, which is rounded and slightly deflected at the lower 

 posterior angle, a row of strong, sharp, abruptly conical teeth of uni- 

 form size; their bases are strongly plicate, their upper portion 

 usually finely reticulated. Between the maxillae and the basilar 

 bar the roof of the mouth seems to have been closed in by a pair of 

 plates like those of Megalichthys, whose surface is set with fine 

 rasp -like teeth, bounded by a row of small, stout, conical teeth. 

 The connexions of these parts are nowhere seen. 



The mandible is a strong bone, deep in front, tapering poste- 

 riorly on both margins; the transversely elongated, saddle- 



