On the Genus Gyracanthus, Agassiz. 37 
breadth of abdomen 8 ; length of tegmina 22, breadth of teg- 
mina 6; breadth of marginal field 1°5. 
_ The above description was drawn up from the living 
insect. 
Hab. Sylhet and North Cachar hills, Assam. 
The specimen has since been compared with the mutilated 
type in the Oxford Museum by Professor Westwood and 
myself, and found to agree perfectly therewith. The discre- 
pancy between Westwood’s figure and the above description 
as to the structure of the discoidal vein of the wings is ex- 
plained by the bad state of preservation of the typical specimen. 
1V.—WNotes on the Genus Gyracanthus, Agassiz. 
By Dr. R. H. Traquair, F.R.S.* 
1, Did Gyracanthus possess dorsal spines? 
Although Agassiz himself pointed out that the spines of 
Gyracanthus were not bilaterally symmetrical, inasmuch as 
one side was more rounded than the other, he nevertheless 
regarded them as dorsal, and so did people in general, until 
in 1863 Messrs. Kirkby and Atthey pointed out the probable 
pectoral nature of some at least of these appendages, the 
grounds for this conclusion being the conspicuous lateral cur- 
vature shown by such specimens, along with the wearing 
away of the apices, as if they had been subject to habitual 
attrition at the bottom of the water in which their possessors 
lived. In 1868 Messrs. Hancock and Atthey returned to 
the subject t, and, reviewing the extensive series of specimens 
in the collection of the last-named gentleman, divided them 
into two categories—first, those with lateral curvature and 
worn apices, and second, those in which apparently there was 
* Read before the Royal Physical Society of Edinburgh, December 19, 
1883. 
+ Ann. & Mag. Nat. Hist. (4) 1868, vol. i. p. 3868. In a footnote 
Messrs. Hancock and Atthey refer to a paper by Messrs. Atthey and 
Kirkby, entitled “ Fish-remains in the Coal-measures of Durham and 
Northumberland,” as having been read before the British Association at 
Newcastle in 1863, and as containing the first suggestion of the paired 
nature of these spines. I cannot find this paper in the British Associa- 
tion’s ‘Proceedings’ for that year; and although a paper of the same 
title is found in the ‘ Proceedings of the Tyneside Naturalists’ Field Club,’ 
it contains no reference to Gyracanthus. These original remarks would 
therefore seem not to have been published. 
