E. D. Wellhum — On Rhadinichthys. 261 



liitherto unknown. In my collection there are many fragmentary 

 remains, collected from tlie Yorkshire Coal-measures, which show, 

 among other interesting points, the form and ornamentation of many 

 of the bones of the head and shoulder-girdle ; while one more nearly 

 perfect specimen shows well the form of the fish and some other 

 points in its anatomy which have not been hitherto described, namely, 

 the relative positions of the dorsal, anal, and ventral fins, the former 

 being very well preserved and perfect. 



From the material above mentionei^. together with that already 

 -desci'ibed by Dr. Traquair, I now think it possible to give a fuller 

 and more detailed description of the fish than has hitherto been 

 possible. 



One specimen in my collection, which shows the fish from a line 

 drawn obliquely upwards and backwards from a point immediately 

 behind the pectoral fin to a point slightly beyond the commencement 

 of the caudal fin, would represent a fish about 55 mm. to 60 mm. in 

 length ; but other fragmentary remains show that the adult fish 

 reached a larger size, probably about 90 mm., and this size 

 corresponds with that given by Dr. Traquair. 



The bones of the head appear to be of the same form and to have 

 the same arrangement as those of other members of tlie genus 

 Bhadinichthjs. The cranial buckler, as shown by specimens in my 

 collection and as pointed out by Dr. Traquair, is ornamented with 

 " tolerably coarse ridges, passing here and there into tubercles." The 

 opercular bones are ornamented in a similar manner, but the ridges 

 appear to be somewhat finer, not so frequently interrupted, and 

 rather more irregular in arrangement. On the maxillee the ridges 

 are moderately coarse, are interrupted at distant intervals, and recur 

 in slightly wavy lines more or less parallel with the inferior border, 

 which does not show any signs of tuberculation. The mandible, as 

 pointed out by Dr. Traquair, is " slender and tapering, sculptured 

 with a few tolei-ably coarse ridges, which, as usual, pass forwards and 

 also obliquely upwards to meet the dentary margin at a very oblique 

 angle." The teeth are small, conical, and somewhat incurved. 



The bones of the shoulder- girdle are of the usual form and 

 arrangement, and are sculptured with ridges which are interrupted 

 at distant and irregular intervals, and which run more or less 

 parallel with the borders of the bones. 



The body is elegantly fusiform, but somewhat elongated, the 

 greatest depth being at a point about midway between the occiput 

 and the commencement of the dorsal fin, the depth here in one 

 specimen in my collection being 10 mm. and the total length of the 

 fish (when perfect) probably about 50 mm. From this deepest 

 region the body gradually tapers to a delicate tail pedicle. 



The scales on the nape appear equilateral ; on the mid-flank they 

 are slightly higher than broad ; on the bell}' they become low and 

 narrow ; and posteriorly they get gradually smaller and more nearly 

 equilateral until on the tail pedicle they assume the usual lozenge- 

 shaped form. The scale ornamentation consists of (1) a few sharply 

 out, faint strias, which run parallel and close to the anterior and 



