%^ REPonT — 1855. 



remains of the Pterygotus have been known in Scotland for more than half a cen- 

 tury, tHe mandibular, or jaw-feet (from their scale-like sculpturing and wing-like 

 shape), being the "Seraphim" of the Forfarshire quarrymen. These and other 

 portions have been in the cabinets of the curious for many years, and were univer- 

 sally regarded as the remains of fishes. Even Agassiz himself looked upon the 

 imperfect fragments originally shown him as ichthyolites ; and it was not till he 

 had an opportunity of examining (in 1834) the once magnificent collection of iVIr. 

 Webster, of Balruddery, that he discovered their true crustacean character, and at 

 once assigned to them a place in PalEeontology, under the title of Palteocarchms 

 alatus; and subsequently, when he saw that the creature had no generic relation- 

 ship to any existing Crustacea, he abandoned the first name for that of Pterygotus 

 problematicus, in allusion to the deceptive nature of the remains. The Pterygotus, 

 of which there appeared to be three distinct species, — the gigantic problematicus, 

 the anglicus, and the punctattis — was altogether diflFerent in its general structure 

 from any known crustacean, living or extinct. The portions chiefly found (atid oi 

 these capital specimens were in the collections of Lord Kinnaird, the Watt Insti- 

 tution, Dundee, &c., all originally from Balruddery) were the frontal cephalic shield, 

 the posterior cephalic or thoracic shield, with its lunar-like epimera, the abdominal 

 segments, generally from seven to eleven in number, the huge prehensile claws, 

 with their curious denticulated edges, attached to limbs of great length, the shorter 

 swimming-limbs, with their paddle-like appendages, and several semi-oval detached 

 plates, which evidently belonged to the breast or under side of the animal. Putting 

 all these pt'ttions in place, as nearly as could be determined, we had a huge lobster- 

 like crustacean — but only lobster-like in general contour, for in its true generic 

 relations it belonged to no existing family in the order. Partly phyllopod and 

 partly pcecilopod, in its abdominal segmentation macrourous, and in its thoracic ap- 

 paratus resembling the existing Liniuhis, the Pterygotus could be classed with no 

 living family, and was in aspect more like the larval than the adult form of any 

 Crustacea with which we wete acquainted. This peculiarity, indeed, ran throughout 

 the whole of the Crustacea (and there were several Dew forms he would notice on 

 another occasion) which had hitherto been detected in this geological horizon — a 

 horizon that would yet be found to be marked peculiarly by its strange Crustacea. 

 From the portions he now exhibited to the Section, the members could perceive at a 

 glance that the restoration by iVIr. M'Coy was altogether erroneous, and bore scarcely 

 any resemblance to what the creature must have been when alive, and acting the 

 part of scavenger along the muddy shores of the Old Red Sandstone seas. The 

 figures on the walls (Mr. Page here exhibited what he conceived to be a near 

 approach to a complete restoration) would afford some idea of the general features 

 of the animal, which he had found of all sizes, from ten or twelve inches up to full 

 five or six feet in length. Such was the Pterygotus ; and, looking at its complex 

 structure, as well as the similar structure of the other Crustacea of the period, there 

 could be no doubt that no existing classification of the order embraced them in its 

 subdivisions. The fact was, that the existing Crustacea were by no means well 

 worked out as a group, and the discovery of these strange fossil forms rendered the 

 study still less perfect. With regard to the second portion of his subject, he would 

 only remark, that, without attempting minute co-ordinations, he was inclined to 

 place the " Pterygotus beds" on the very lowest verge of what had hitherto been 

 regarded the Old Red Sandstone or Devonian system. It was true, that some high 

 authorities were inclined to rank these beds as Upper Silurian, that is, on the very 

 highest stage of the Silurian system ; and so far as the working out of the beds were 

 concerned, it mattered little whether they were regarded as loivest Devonian or upper- 

 most Silurian ; but this he might observe, that so long as the Cep/ialaspis was re- 

 garded as a true Old Red ichthyolite, geologists were bound to rank the Pterygotus 

 beds as the base of that system. In Scotland, the Cephalaspis and Pterygotus were 

 invariably found in the same strata ; and for this reason he had hitherto contended 

 for the "Tilestones" of the English geologists being restored to the Devonian 

 system, where they had originally been placed. Taking this vievv, we had a well- 

 marked zone of grey fissile flags and tilestones, of slaty marls and laminated shales, 

 everywhere in Scotland and England subjacent to the true " Old Red," and as de- 

 cidedly superior to the shales and limestones of Siluria, characterized as these were 



