CANOBIUS CRASSUS 181 



scales as in several other species of the genus ; they are mostly smooth and flat — 

 sometimes, however, the surface appears somewhat corrugated, but this I look on as a 

 result of slight post-mortem distortion. The posterior border is sharply and minutely 

 denticulated, the grooves between the denticles being sometimes prolonged forwards for 

 a little distance over the surface. 



Observations, — The only Carboniferous fish with which the present species could be 

 confounded is Rhudinichthys carinatus, which occurs abundantly in the same shale and 

 in the same state of preservation ; but the contour of Canobius macrocephalus is 

 characteristic. Its alliance with Canobius pulchellus and C. politus is in reality much 

 more intimate. 



Geological Position and Locality. — Abundant in the "Curly" Shale at Pumpherston 

 and Roman Camp in the Broxburn district, West Lothian. Type specimen in the 

 Collection of the Author. 



5. Canobius crassus, sp. nov., Traquair. Plate XL, fig. 5. 



Description. — The length of the unique specimen represented in PI. XL, fig. 5, is a 

 little over 3|- inches, but, as the head is squeezed a little backwards on the body, we 

 may infer that its original length must have been a little more ; the greatest depth 

 of the body equals 1^ inches. The general form is deeply fusiform, the contour of the 

 back between the occipital region and the dorsal fin being gently rounded or arcuated. 



Excepting a faint trace of the ventral between the anal and the region of the 

 pectoral, there is nothing to be seen of the paired fins. The median fins are rather 

 small; the dorsal and anal exhibit the usual triangular-acuminate contour; the caudal 

 is heterocercal and deeply cleft ; the rays of all the fins are delicate, distantly 

 articulated and smooth on their surfaces. 



The scales are rather small for the size of the fish ; they are mostly smooth, though 

 in some places we see the impressions of minute contorted ridges on the anterior part 

 of the surface. There are a few large median dorsal scales just in front of the dorsal 

 fin, but these do not form a line extending the whole distance to the occiput. The 

 scales of the flank are prominently denticulated along their hinder margins. 



Observations. — The above-described unique specimen is a sharp impression or 

 "counterpart" representing a fish which I cannot refer to any hitherto described 

 species, though I have no hesitation in referring it to the genus Canobius. Perhaps it 

 resembles Q. politus more than any other, but it difiers conspicuously by its deep, 

 highly arched body and small fins. 



Geological Position and Locality. — From the Calciferous Sandstone Series, Glen- 

 cartholm, Eskdale, in the Collection of the Author. 



[Owing to the death of the Author when the Monograph had been completed thus far, the 

 following concluding paragraphs are compiled from his published papers.] 



27 



