262 



E. D. Wellhuvn — On RJiad'michthys. 



inferior borders, and (2) four or five ridges wbicli commence at the 

 posterior denticulations and run forward for some distance across 

 the scale, the ridges becoming somewhat more oblique from below 

 upwards. This sculpture is most strongly marked on the scales of 

 the nape, but from this point it gradually appears to become fainter, 

 the 8tria3 parallel with the anterior and inferior borders being first 

 lost ; the ridges then become fainter and less marked, but the 

 posterior denticles, although they become less in number, appear ta 

 be present on the scales far back on the body near the tail pedicle. 



The pectoral fin, as pointed out by Dr. Traquair, appears to have 

 been " of moderate size and its principal rays unarticulated until 

 near their termination." The ventral fins are not well shown in 

 any specimen, but one in my collection shows a trace of one of these 

 fins, though not in a condition to permit of a detailed description : 

 it appears to have been small and delicate. The dorsal fin is 

 beautifully shown in the specimen mentioned above : it commences 

 at a point very slightly in advance of the anal fin, the two fins 

 being nearly opposed to each other. This fin is of moderate size, 

 acuminated, concavely cut out behind, and composed of delicate rays 

 which dichotomize distally, the terminal branches of the rays being 

 very fine. The rays are distantly articulated, and show a single, 

 sharply cut, longitudinal furrow. The anal fin in the same specimen 

 is more imperfect, but a fin of similar form and construction i& 

 indicated. The caudal fin in the above specimen commences at 

 a point about 17 mm. behind the commencement of the dorsal fin, 

 but unfortunately only the proximal portion of the fin is shown. 

 According to Dr. Traquair, the "rays are delicate and their articula- 

 tions rather distant." 



T^^<v>-^lfc' 



Shadinichthys moncmis, Egerton. Twice natural size. 

 D F, dorsal fia ; a f, anal fin ; y f, ventral fin ; x p, tail pedicle. 



In the Yorkshire Coal-measures this fish is mostly found in a very 

 fragmentary condition ; but it has a wide distribution, and occurs m 

 the shale above the following coal-seams : — > 



