RHADINICIITHYS MONENSIS. 137 



General Observations. — RhadlnicIitliJ/s canobie'nsis belongs to the '^ carinatus'' 

 group, but is evidently specifically distinct; the question is as to whether eleganluUis 

 and (lelicafulics should have the rank of species or of varieties. I have done my best 

 with this question and consider my solution of it to be the best, or at least the most 

 convenient that can be offered in the meanwhile, believing that in such cases it is better 

 to be a " slumper " than a "splitter." 



As regards elcf/antulus, it differs mainly from the typical form in the much smaller 

 development of the low narrow scales in the ventral region, a distinction which I can 

 hardly consider to be necessarily specific. Nor do I think it exactly safe to maintain 

 delicatiih(s as a " species " on account of the slight difference in the sculpture of the 

 scales. 



4. Rhadinichthys MONiiNsis, Egerton, sp. Plate XXXI, figs. 3 — G. 



Pal^eoniscus moxensis, Ejerton. Quart. Joiini. Geol. Soc, vol, vi, 1850, p. 5, 



pi. i, fig. 3. 

 Rhadinicuthts 1I0NEN3IS, Traquair. Proc. Eoy. Pliys. Soc. Edinb.,vol. iv, 1878, 



p. 211. 

 ~- — J. Ward. Trans, N. Staffs. Inst. Mining Engin., vol. 



X, 1890, p. 175. 

 — • — A. S. Woodward. Cat. Foss. Fishes Brit. Mus., pt. 



ii, 1891, p. 467. 

 — — E. B. WeUburn. Geol. Mag. (4), vol. vii, 1900, pp. 



260-263, and Proc. Turks. Geol. 

 and Polyt. Soc, vol. xiv, 1901, 

 pp. 168, 174. 



Description. — Only the detached scales were known to Sir Philip Egerton, the 

 founder of the species, which, according to the state of knowledge at the time, he 

 referred to the genus Palaoaiscus. His brief description may here be quoted in full : 



" Palaoniscus monensis Egerton, Pi. I, fig. 3. Lord Enniskillen found the 

 specimens from which this species is named in the shale brought oat of a coal-pit in the 

 Isle of Anglesea, near the Flolyhead Road a few miles from the jMenai Bridge. They 

 are single scales which belonged to a larger fish than P. Egertoni and differ in e.Kternal 

 characters from those of that species. The surface is traversed by regular parallel 

 grooves, the ridges between these terminating in cusps at the posterior margin. In 

 addition to these a series of fine lines is distinctly seen bordering two sides of the scale, 

 apparently indicating the annual increment." 



The sculpture of the scales, however, leads us at once to thiidc of Rkaditiichthgs as 

 the genus to which the fish that bore these scales belonged, and this position is 

 established by the remains of the species which have turned up since Sir Philip Egerton 

 wrote the above-quoted words. 



