64 Royal Physical Society of Edinburgh. 



state of keeping, and furnished a better basis for the restoration of 

 the animal. Its head was covered with strong dermal plates of bone, 

 fretted on the exterior surface by the star-like tubercles to which the 

 creature owed its name ; its jaws were furnished by a thickly-set 

 outer row of Jish teeth, and an inner thinly-set row of huge reptile 

 teeth ; a single plate of vast size protected the under part of the head, 

 filling up the arch-shaped space formed by the semicircular sweep 

 of the lower jaw ; its gill-covers, like those of the sturgeon, were 

 composed each of a single plate ; — like a contemporary fish of the 

 same family, the Glyptolepis, it had a strong shoulder-bone (the ana- 

 logue in fishes of the os humerus in quadrupeds and the human sub- 

 ject), and its body was covered with delicately fretted scales inter- 

 mediate in their style of carving between those of the Holoptychius 

 and Glyptolepis. The true skull of the animal was apparently a mere 

 cartilaginous box, of which no fragment survives, but in the exterior 

 cranial plates there might be traced what seemed to be analogues 

 of the frontal -superior, frontal- anterior, and parietal bones. The 

 eye orbits were placed, as in many of its contemporaries, immediately 

 over the upper jaw ; and, as in Coccosteus, Diplopterus, and Osteolepis, 

 a small well-marked plate occupied the centre of the space between. 

 The external lines of the frontal buckler did not always indicate lines 

 of suture, but in some cases seemed purely ornamental ; and the rep- 

 tile teeth of the creature, as, in the absence of specimens establishing 

 the point, had been shrewdly anticipated by Agassiz, indicated the 

 true Dendrodic character. One very curious bone, which had its 

 place probably over the shoulder, greatly resembled the dorsal spine 

 of one of the huger Placoids of the Carboniferous system, — the Gyra- 

 canthus ; it was similarly furrowed by diagonal groovings ; but not- 

 withstanding the resemblance, it was evidently not an ichthyodorulite, 

 but lay flat on the body of the creature in the character of a plate. 

 As shown by numerous coprolites found in the same bed with the 

 remains of Asterolepis, and which, from their great size, could have 

 belonged to none of its contemporaries, the animal had possessed, 

 like existing sharks and rays, and some of the extinct Enaiosaurians, 

 the spiral disposition of intestine ; and the broken fragments of 

 scales of Dipterus, palpably present in their convolutions, demon- 

 strated, what might, indeed, be inferred from its formidable teeth, 

 carnivorous habits. Mr. Miller stated that the bulk of some of the 

 individuals of this genus must have been enormous ; and he was the 

 more desirous, he said, to draw attention to the fact, as he had men- 

 tioned in his little work on the Old Red Sandstone, founding on a 

 large amount of negative evidence, that the fishes of the Lower Old 

 Red Sandstone were characterized generally by a mediocrity of size. 

 Single occipital plates found by Mr. Dick, in the neighbourhood of 

 Thurso, measured sixteen and a half inches, and a corresponding 

 plate, in the collection of Professor Asmus, at Dorpat, two feet across ; 

 whereas in the very massive specimen of Holoptychius, found by the 

 Rev. Mr. Noble of St. Madoes, at Clashbennie, and now in the Bri- 

 tish Museum, the two plates by which this single plate of the Aste- 

 rolepis is represented, measure only four and a half inches. Mr. 



