Dr. R. H. Traquair — New Fish Remaim from Borough Lee. 541 



As usual, a rounded central cavity commences at the base and 

 extends towards the apex. 



I accept, provisionally, Mr. J. W. Davis's amalgamation of the 

 genera Fleur acanthus and Or th acanthus, Ag., the fact being that we 

 have as yet no accurate clue to the genera of Carboniferous Pleura- 

 canthidce. The present species is evidently related, in its general 

 form, to PL rohnstus and denticulatus of the last-named author,^ as 

 well as to 0. arciuitus of Newberry,^ though differing from all of 

 them in the delicate adpressed form of the denticles. My collection 

 contains three entire specimens and many fragments of this very 

 pretty spine. 



Pleuracanthus horridulus, n.sp. 



Length of the most perfect specimen which has occurred 1 inch, 

 but the completeness of its base is doubtful ; diameter, -jV inch 

 at apparent base ; contour gently arcuated, tapering to a fine 

 point ; surface tolerably boldly striated for rather more than 

 half the length of the spine, then becoming smooth, with occasional 

 elongated punctures. Posterior or concave margin set, from the 

 apex to one-third of the length from the base, with two rows of 

 proportionally large and prominent sharp, recurved denticles. Of 

 these there are eight or nine on each side. They diminish in size 

 towards the apex, but not in proportion to the attenuation of the body 

 of the spine, so that distally they may appear as long as the spine is 

 thick. These two rows of denticles are placed so close together 

 along the posterior margin of the spine, that when a specimen is, as 

 is iisually the case, seen lying on its side on the matrix, it is difficult 

 to conceive that there is more than one row ; nevertheless, on a 

 portion of a spine which has started off, the presence of two rows is 

 proved beyond all doubt, the denticles of each row alternating with 

 each other. 



Tliis formidable-looking little spine bears a very considerable 

 resemblance to the figure given by Prof. Newberry of Compsacanthus 

 Icevis, Newb.,^ notwithstanding the obvious specific distinction that 

 in the latter the denticles are more numerous, and diminish regularly 

 towards the apex in proportion to the attenuation of the diameter of 

 the spine itself. Prof. Newberry states, however, that in C. IcBvis 

 there is only one row of denticles, and on this fact he has founded 

 the genus Compsacanthus. The existence of two distinct rows, 

 however closel^'^ placed, in the present fossil, necessitates its reference 

 to Pleuracanthus (incl. Orthacanthus). 



Cynopodiu's crenulatus, Traq. 

 Cynopod'ms crenulatus, Traq. Geol. Mag. Dec. II. Vol. YIII. p. 35. 



Besides the typical arid most abundant form of this strange 

 spoon -shaped body which I described in a previous communication, 

 specimens not unfrequently occur which are aberrant in their 

 contour. In some of these, while the general shape is similar to 



1 Quart. Joirrn. Geol. Soc. xxxvi. 1880, pp. 330 and 334. 



2 Pal. Ohio. vol. i. p. 332, pi. 40, fig. 4. 



3 Pal. Ohio, vol. i. p. 332, xA. 40, figs. 5, 5a. 



