4 



BRITISH FOSSILS. 



mention of lateral jugular plates; the scaleS; wliicli are as often 

 oval as rliomboidal, are sculptured in a very different manner from 

 those of Glyptolwmus, and, according to Pander, tlie anterior edges 

 of the median fins are provided with fulcra. 



Glyptopomus (Agassiz) is another genus whose close alliance with 

 Giyptolcemus is evidenced by the structure of its skull, of which 

 there is a fine specimen in the British Museum. It is very depressed 

 and has two distinct frontal bones, separated anteriorly by a small 

 rhomboidal plate ; there are two long and distinct parietals, and 

 three bones, one median and two lateral, behind these, covering 

 the occiput. The orbits are situated far forward, the gape is greatly 

 elongated, there are two principal jugular plates, and the pectoral 

 arch is as in Glypjtolwmus. A fine specimen in the Museum of 

 Practical Geology shows that some of the teeth, at any rate, were 

 of large size, and longitudinally grooved at their bases. 



Fig. 4. 



Only three specimens of Glyptopomus are at present known, and 

 no one of these exhibits either the paired or the median fins ; but 

 the close correspondence of the cranial structure of this genus with 

 that exhibited by Glyptolmmus , leaves no doubt on my mind that, 

 when discovered, the fins will be found to be similar, in all essential 

 respects, to those of the latter genus {see note, p. 46). The sharply 

 rhomboidal scales are thicker in proportion than those of any other 

 Devonian fish, and are pitted upon their surfaces like the scutes of 

 the Crocodilia. 



