746 Davis — On the Fossil Fish- Remains of the Coal Measures of the British Islands. 



The spine described by Mr. Thomas Stock* as Lophacanthus Taylori was from 

 the Lowmaiu Coal Seam. The writer has not had an opportunity to inspect the 

 original, but the woodcut with which the description is illustrated indicates a close 

 resemblance to the spine in the Atthey collection. The section as illustrated by the 

 woodcut, is different, but that may be perhaps accounted for by the imperfection 

 of the specimen. The relationship between these spines being so close, I feel 

 justified in including them under the specific name given by Mr. Stock; but as 

 I am convinced that they are not generically distinguishable from the spines of 

 Pleur acanthus, they must be included in that genus. 



Formation and Locality. — Coal Measures, Airdrie; LowmainCoal Seam, Newsham. 



Ex coll. — Natural History Department, British Museum ; Mr. Joseph Taylor, 

 of Shire Moor ; Museum of Natural History, Newcastle. 



Pleuracanthus (Compsacanthus) triangularis, Davis. 



(PI. Lxxin., fig. 24.) 



Compsacanthus triangularis, . Davis, J. W., 1880, " Quart. Journ. Geol. See," 



vol. xxxvi., p. 62 (woodcut). 



Spine : straight, robust, upper part perfect ; base somewhat crushed ; 0"063 m. 

 in length ; greatest diameter O'OOo m. midway between the extremities ; distally it 

 gradually contracts, and ends in a point. The base is hollow, and the walls are 

 thin ; the internal cavity apparently terminal. The lateral surfaces of the spine 

 are compressed anteriorly, which gives it a triangular form in section. The 

 posterior surface, from which springs a single median row of denticles, is rounded. 

 The denticles are broad at the base, compressed laterally, ending in an obtuse 

 point. 



This spine, which still remains unique, was found in the Cannel Coal of 

 Tingley; it was included in Dr. Newberry's genus Compsacanthus, ■\ characterized 

 by having only a single row of denticles on the posterior surface of the spine. 

 Compsacanthus Icevis, Newb., is circular in section, and there are a considerable 

 number of denticles diminishing in size from the lower towards the upper part of 

 the spine. In this species the number of denticles is small, and the spine is 

 more or less triangular in section. 



Dr. Zittel has expressed the opinion that probably Compsacanthus will be 



* Ann. and Mag. Nat. Hist., ser. v., vol. v., p. 217. 



f Proc. Acad. Nat. Sci. Philad., p. 100, 1856 ; Kept. Geol. Survey, Ohio, vol. i., pt. ii, p. 332, pi. xl., 

 fig. 5, 1873. 



