542 I)7\ R. H. Traquair — New Fish Remains from Borough Lee. 



that of the ordinary type, the radiating grooves and marginal crenu- 

 lations of the expanded portion are wanting or obsolete, while the 

 surface is also deficient in the usual glossy ganoine layer, and is 

 dull, and more or less roughened by minute pores and short wavy 

 grooves. In some of these cases the expanded portion is abruptly 

 truncated. There is, however, no ground whatever for considering 

 that any of these varieties in form are indicative of specific difierence. 

 Cynopodius crenulatus, besides occurring in the Borough Lee 

 Ironstone (Carboniferous Limestone series), is found also in the 

 underlying Calciferous Sandstone series of the Edinburgh district, 

 as at Straiten Brick work (Mr. J. Gibson), Straiten Old Shale works 

 (coll. of the author), Inchkeith (Mr. James Gaul), Pitcorthy Shale 

 works (Mus. Sc. and Art Edinb.). 



Gy r acanthus formosus, Ag. 



The opinion that Gyracanthus formosus and tuberculatiis of Agassiz 

 are not specifically distinct from each other, having been expressed 

 by more than one author, and I myself not having any particular 

 reason for dissenting from that view, I catalogued the Gyracanthus 

 spines, which are of such frequent occurrence in the Borough Lee 

 Ironstone, as G. tuherculatus, in the list prefixed to my first paper on 

 the fish remains of this bed. But whether the specific identity of 

 these two forms be accepted or not, it seems to me, on reflection, 

 necessary to preserve the name /ormosws, as it certainly occurs first 

 in Agassiz's list, and may therefore claim priority. 



It has long ago been pointed out that many at least of the spines 

 of GyracatitJius were in all probability pectoral in their nature, by 

 reason of their marked lateral curvature, and the frequency with 

 which their extremities are found to be rubbed and abraded, as if 

 they had been dragged along the bottom by a habitually ground- 

 dwelling fish.' Messrs. Hancock and Atthey, however, still retained 

 as probably dorsal a number of spines in which no lateral curvature 

 is observable. 



But Agassiz himself had already noticed another important cir- 

 cumstance connected with the want of lateral symmetry in Gyra- 

 canthus formosus. He says, " Leur coup est irreguliere, I'un 

 des cotes etant un peu plus renfle que I'autre." ^ This asymmetry of 

 form is well marked in the Borough Lee specimens. Along the 

 anterior aspect runs a line from which the ornamental ridges diverge, 

 along the posterior is a keel or ridge set with small, closely placed, 

 recurved denticles, and ending on one side of the extensive basal 

 excavation. The lateral distance between these two lines is greater 

 on one side than on the other, so that, in transverse section, one side 

 is seen to be more gibbous, the other narrower and flatter : more- 

 over, on the gibbous side a well-marked shallow longitudinal exca- 

 vation or gx'oove runs along immediately contiguous to the denticu- 

 lated ridge. In fact, this groove appears to correspond to the 

 posterior flattened area of such spines as Ctenacanthus, but set on 



1 Hancock and Attliey, in Ann. and Mag. Nat. Hist. (4) vol. i. 1868. 



2 Poissons Fossiles, vol. iii. p. 18. 



