2 



BRITISH FOSSILS. 



former, as indeed it is represented by both Leske and Parkinson, being 

 much nearer the posterior margin, and the ambulacra much narrower 

 than in N. carinatus. The Nucleolites columbaria of Lamarck was a 

 species very insufficiently described by that author, who cites no figure, 

 and mentions that it is found as fossil in the environs of Mons. In 

 Count D'Archiac's valuable report on the fossils of the Tourtia, a 

 remarkable cretaceous conglomerate found in Hainault and a part of 

 French Flanders, a detailed and most excellent description is given of 

 the Nucleolites columharius of Lamarck, which is there distinguished 

 from the Nucleolites carinatus of Goldfuss, from which it is stated to 

 differ in its general form being more elongated, more depressed, and 

 consequently less globular. Excellent figures are at the same time 

 given, which, however, so closely resemble one of the commonest forms 

 of our English carinatus^ and certainly one not distinct, that I do not 

 venture to separate the species ; nor does the accompanying descrip- 

 tion contradict their identification. One point only in the figure seems 

 to differ ; the upper margin of the anus is not so prominent in the 

 French specimens as in ours. M. Desmoulins is quoted by M. D'Archiac 

 as having identified the species of Goldfuss with that of Lamarck. In 

 the " Catalogue Raisonne des Echini des," the Catopyyus carinatus is 

 regarded as distinct from the (7. columharius, and the figure of D'Archiac 

 is cited for the latter. Under the synonyms of the former, the name 

 " Nucleolites hritanna, Defrance," is cited, and as a variety, " minor : 

 Nucleolites ovulum, Defrance." Nucleolites {Catopygus) carinatus was 

 first enumerated as a British species by Morris in the " Catalogue of 

 British Fossils." In the " Index Palseontologicus," Bronn cites N. 

 columbaria, Lamarck, as a questionable synonym of carinatus, retaining 

 at the same time Catopyyus columharius of Agassiz, for which he refers 

 to D'Archiac's figure and description as a distinct species. In England, 

 so far as I have seen at least, we have only the one species of this sec- 

 tion of Nucleolites, and that one so variable in its outline that we are 

 naturally led to suppose too many species have been made out of it on 

 the Continent. 



Description. — Outline varying from ovate to subrotund, always more 

 or less widening out posteriorly, least so in vars. y and ^. Back tumid, 

 varying in degree of elevation ; in some specimens, especially of var. /S, 

 subdepressed and declining anteriorly, in others subconic and much 

 elevated in the centre, when the true apex is almost at the same spot 

 with the highest point ; the latter is usually, however, behind the ovarian 

 disk. The apex is always more inclined to the front than to the posterior 

 extremity. The sides, in all the varieties among British examples, are 

 rounded with a very slight degree of compression in all varieties. The 

 posterior extremity is truncated more or less abruptly. A more or less 



