178 GANOID FISHES OF THE CARBONIFEROUS FORMATION. 



both fins are well developed, triangular-acuminate, composed of rather stout smooth 

 rays which dichotomise towards their extremities and are divided by tolerably distant 

 articulations. The caudal is deeply cleft, very heterocercal and inequilobote, the upper 

 lobe appearing produced ; its rays are similar in character to those of the dorsal and anal. 

 Very distinct fulcra are seen along the anterior margins of all the fins described. 



Several examples have occurred of what seems to me to be only a variety of the 

 above described form, the only appreciable difference being the more delicate markings 

 on the scales (PI. XXXIX, figs. 10, 11). 



Observations. — I know of no previously-described fish with which the present species 

 can be confounded. In general contour it resembles Canobius Ramsayi and 

 C. eleyantulus, but it may at once be distinguished from both by its scale-markings as 

 well as by the more typically Palasoniscoid configuration of its facial bones. In the 

 form of the opercular bones and the direction of the suspensoiium, a condition is 

 presented which is somewhat intermediate between that in Canoblus Ramsayi and in 

 ordinary Palaeoniscidse, and which did induce me to make a separate genus " Mesopomd" 

 for this and the three following species. Rut considering that so much still remains to 

 be learned concerning the more minute characters of these small fishes, it is perhaps 

 better to avoid premature multiplication of genera by including them provisionally in 

 Canobius, to which they certainly bear a greater general resemblance than to any other 

 generic form. 



Geological Position and Locality. — Near Glencartholm, Eskdale, in the fish-bearing 

 beds of Lower Carboniferous age exposed in the banks of the River Esk. 



k Canobius politus, Traquair. Plate XXXIX, figs. 12 — 10. 



Canoisius I'OLItus, Traquair. Trans. Roy. Soe. Ediub., vol. xxx, 1881, p. S3, pi. v, 



figs. 14—10. 

 Mesopoma politum, Traquair. Ann. Mag. Nat. Hist. [6], vol. vi, 1890, p. 493. 

 Canobius politus, A. S. Woodward. Cat. Eoss. Fishes Brit. Mus., pt. ii, p. 433. 



Specific Characters. — Attaining a length of 3 inches, sometimes a little more, the 

 general proportions being those of the genus. Flank-scales mostly smooth and sharply 

 denticulated along the posterior border ; sometimes showing traces of transverse 

 striation ; median scales of the back, between the head and the origin of the dorsal fin, 

 not specially large and prominent, excepting a few just in front of that fin. 



Description. — The type specimen, deficient in the caudal extremity, is represented 

 in PI. XXXIX, fig. 1.2. Subsequent work by various collectors has, however, provided 

 a good many with tails, of which two belonging to the British Museum are shown in 

 figs. 13 and 14 of the same plate. 



