NEMATOPTYCHIUS GREENOCKI. ie) 
wide, measuring one inch across, and the number of its rays may be estimated at no 
less than thirty-five. 
The dorsal fin is placed very far back, being nearly opposite the anal. Triangular- 
acuminate in form, it consists approximately of about forty-five rays, which are rather 
coarser in the anterior two thirds of the fin, but become finer posteriorly. The trans- 
verse articulations of the individual rays are rather close together, but the joints are 
still longer than broad, and the whole ray bifurcates a little beyond its middle. 
The anal fin is the counterpart of the dorsal in form and structure, but appears to 
be very slightly larger. ‘The form and position of these two fins are well seen in 
Pl. XXVI, fig. 2, which is from the “Dunnet”’ Shale of Straiton, and represents 
a smaller specimen. 
The caudal fin, seen most completely in fig. 2, is large, deeply cleft, and strongly 
heterocercal. 
All the fins are set with small, yet distinct fulcra along their anterior margins, and 
these are also best seen in fig. 2, which is taken from a shale specimen and not from one 
preserved in clay ironstone, like most of the others on the same Plate. 
Remarks.—In his ‘ Poissons Fossiles,’ vol. i, p. 78, Agassiz referred to a species of 
** Pygopterus”’ as occurring in the Carboniferous Shales of Newhaven (Wardie), near 
Edinburgh, which he named P. Greenocki, in honour of Lord Greenock, the first 
collector of ichthyolites from that locality, and in whose collection the specimens were 
contained. 
“ Pygopterus Greenocki” belongs, however, to the category of ‘* nomina nuda,” as 
he did not accompany it by any valid description, saying merely that it was an “ Hspéce 
trés-distincte sous le rapport spécifique mais douteuse sous le rapport generique. Les 
fragmens connus ne sont guére que des tétes avec la partie antérieure du tronc. 
Les écailles quai recouvrent cette partie du corps sont plus hautes que longues, et different 
par la de celles de tous les autres Pygopterus.’ Nevertheless, I think we may with 
tolerable, if not with absolute, certainty identify with this ‘* Pygopterus”’ certain heads 
of a large Palzeoniscid from Wardie, presented by Lord Greenock to the Royal Society 
of Edinburgh, and now in the teaching collection of the Geological Department of 
Edinburgh University. 
Having had the good fortune to find at Wardie two entire specimens, I devoted my 
first palzeichthyological paper to a description of these remains, in which I showed that 
the cranial osteology of this so-called “ Sauroid”’ was on the same lines as in fishes 
referred by Agassiz to Amblypterus, one of his so-called “ Lepidoids.” In that paper I 
retained the generic name Pygopterus for the large Paleeoniscid in question, as unfor- 
tunately I had not at that time enjoyed the opportunity of studying the characters of 
the typical Pygopterus of the Marl Slate and Kupferschiefer. However, some years later 
(1875) I showed that the species Greenocki could not possibly be classed in the genus 
Pygopterus, and established therefore the new genus Mematoptychius for its reception. 
