338 Dr. Traquair — On Psep/wdns ma gnus, from E. Kilbride. 



Lord Enniskillen to Messrs. Morris and Eoberts, and published by 

 them in the Quart. Journ. of the Geological Society, vol. xviii. 1862, 

 pp. 99-102. From this list it appears that out of the previously 

 quoted species of Cochliodus, except the first, C. contortus, a number 

 of new genera, as well as several additional species, were established. 

 Cochliodus magmis from Armagh became Psephodiis magnus, with 

 which Helodus planus was merged ; C. magnus from Bristol became 

 Tomodvs convexus ; C. acutus became Deltoptychius acutus and 

 gibberuhis ; C. ohlongus became Streblodus ohlongus, Colei and 

 Egertoni ; and lastly, for C. striatiis, the genus Xystrodus was pro- 

 posed. 



Teeth undoubtedly generically identical with Agassiz's Pseplwdiis 

 ■were in 1866 figured by Messrs. Newberry and Worthen, under the 

 name of Aspidodus crenidatus.^ The authors refer to the resemblance 

 which these teeth bear to Agassiz's Cochliodus magnus, and suggest 

 that the latter, as well as Helodus planus, should be included in 

 Aspidodus. In this Messrs. Newberry and Worthen would have been 

 perfectly right had Psephodus been a mere MS. name like so many 

 others which Agassiz left behind him at Florence Court. For though 

 no definition of Psephodus appeared along with the publication of 

 the name in 1862, its type species, magnus, had been sufficiently well 

 figured and described by Portlock and M'Coy to enable naturalists 

 throughout the world to identify the genus. We may, therefore, 

 grant priority to Agassiz's name, though solely on the grounds above 

 given. And in the sixth volume of the Geological Survey of Illinois 

 the name Aspidodus, given by Messrs. St. John and Worthen, is 

 relinquished in favour of Psephodus. 



It is indeed much to be regretted that Agassiz did not himself 

 publish figures and descriptions of the numerous genera and species 

 of fossil fishes to vphich in various collections he affixed MS. names, 

 and in hardly any department did the non-completion of his work 

 hinder progress more than in the case of those selachian remains 

 from the Carboniferous Limestone contained in the Florence Court 

 collection. Many of those names given by him in his revision of 

 1859 became current among collectors without their having any pub- 

 lished means of verifying their identifications, and the names them- 

 selves being MS. names still, in spite of their publication by Messrs. 

 Morris and Eoberts, were liable at any moment to be superseded. 

 This want has, however, been supplied by Mr. J. W. Davis, who, 

 having been entrusted by Lord Enniskillen with the task of working 

 up the Carboniferous limestone selachian remains in his collection, 

 last year published descriptions and figures of the genera and species 

 there named by Agassiz, along with many others established by him- 

 self as new. The Enniskillen collection itself having been recently 

 acquired by the British Museum, the scientific public at large have 

 now ample opportunity of knowing the present condition of this 

 branch of palseichthyological science, so far at least as specimens 

 from British Carboniferous rocks are concerned. 



1 Geological Survey, Illinois, vol. ii. p. 92. 



