24 CARBONIFEROUS TRTLOBITES. 



short, mucronate, obtuse point ; axal lobe nearly as wide as the lateral ones ; 

 about fifteen axal and nine lateral segments ; surface smooth. 



" This is the only Trilobite I know of in the Mountain-limestone with a 

 mucronate or pointed tail. Length of pygidium four lines, width five lines." 



We are indebted to Professor R. H. Traquair, M.D,, F.R S., &c., for a very care- 

 fully prepared resume of the literature of this species, from which we make the follow- 

 ing extract (' Journal of Roy. Geol. Soc. of Ireland,' Vol. II, New Series, p. 213). 



" In the year 1844 M'Coy figured, under the name of PhilUpsia mucronata^ the 

 pygidium of a Trilobite from the Irish Carboniferous Limestone, and which he 

 considered as new, remarking that he was acquainted with no other Carboniferous 

 form having the caudal extremity prolonged, as in this instance, into a pointed 

 spine or mucro.^ But a trilobite, apparently the same as this, had previously 

 been known to Continental observers under a different name ; for, in 1840, we 

 find Eichwald^ mentioning a Carboniferous trilobite from Bystriza, in the Govern- 

 ment of Novogorod, in Russia, in which the tail is prolonged into a long pointed 

 spine, and whose cephalic shield has on each side a long process. The name 

 quoted for this species is Otarion Eichivaldii (Fischer), but the description is, 

 indeed, sufl&ciently vague, and is not accompanied by any figure. However, in 

 1845, Verneuil,' in figuring and describing as ' PhilUpsia Eichwaldii ' a pygidium, 

 to all appearance belonging to the same species as the Irish specimen, put aside 

 the name ' mucroyiata^ (M'Coy) as a synonym of 'Eichwaldii' (Fischer). This 

 example was followed by Bronn* and by Morris,^ and the remains of this species, 

 not uncommon in many British localities, are at present very generally labelled 

 and catalogued as PhilUpsia or Griffithides Eichivaldii. 



" On turning back, however, to Fischer's original description and figure of 

 Asaphus Eichwaldii from Vereia, in the Government of Moscow, published in 

 1825," we are surprised to find a rounded pygidium represented and described. 

 The head is spoken of as unknown, but as regards the tail we read : ' Cauda 

 depressa, suhrotundata segmentis tredecim ad quatuordecim, margine angustato, 

 sulco infra profundo.' Again, in 1837,^ the same pygidium was figured and 

 described by Fischer. The figure looks as if it were taken from the same specimen 

 represented in the former work, although the rounding of the caudal extremity is 



^ ' Synopsis of the Carb. Toss. Irel.,' pi. iv, fig. 5. 



2 " Die Thier- und Pflanzenreste des alten Eothen Sandsteins und Bergkalks im Xowogorodischen 

 Gouvernement." ('Bull. Sci. de St.-Peterb.,' 1840.) 



8 ' Geol. de Eussia ' (1845), vol. ii, p. 376, t. xxvii, fig. 14. 



* ' Index PalseoDtologicus.' Stuttgardt, 1848, vol. ii, p. 958. 



5 ' Cat. Brit. Foss.' London, 1854, p. 109. 



•^ Contained in a work by Eichwald, entitled ' Geoguostico-zoologicte, per Ingriam marisque Baltic! 

 provineias, nee non de Trilobitis observationes.' Casan, 1825, p. 54, t. iv, fig. 4. 



7 ' Oryctographie du gouvernement de Moscou,' p. 120, pi. 12, fig. 2, a, b. 



