BRITISH FOSSILS. 



5 



become involved in a labyrinth of names, several of which are ■unaccom- 

 panied by either descriptions or figures, a state of things more likely 

 to retard than to advance our palseontological studies. Lastly, in the 

 " Annals of Natural History," for December, 1848, three new British 

 oolitic Nucleolites are described by Mr. M'Coy, under the names planu- 

 latus, pyramidalis^ and cequalis^ all of which I cannot help surmising will 

 prove, on closer examination, but varieties of clunicularis. The second, 

 N. pyramidalis^ from the cornbrash of Weymouth, has been identified 

 by Mr. M'Coy with the figure on our plate, he having kindly replied to 

 that effect to my inquiries on the subject. In his Paper he remarks, 

 " This resembles the N. clunicularis (Smith, sp. Clypeus lohatus^ Flem.) 

 in the long, deep, narrow posterior sulcus, extending quite from the 

 vertex, but is wider and more quadrate, the base having exactly the 

 form of the N. scutatus, Lamarck ; from the latter it difiers in the strong 

 sulcus uniting the pores, as in most of the genus, and from both species 

 it is distinguished by its pointed elevated apex, and the straight declivity 

 of the posterior side." On this passage I would remark that, in the first 

 place, the name clunicularis is not given by Smith, whose figure (without 

 a name) probably represents dimidiatus ; that Clypeus lobatus^ Fleming, 

 was a name given by that author to a species he considered distinct from 

 his clunicularis^ " Smith," as I have already shown ; that " a strong 

 sulcus" unites the pores quite as much in the var. scutatus as in var. 

 pyramidalis ; and that the degree of elevation of the apex and declivity 

 of the posterior side varies not only in every variety, but in almost 

 every specimen, among the many I have examined,* of all the varieties 

 of this variable species. 



Description. — Outline suborbicular, with a tendency to quadrate, 

 broadening out slightly, and more or less bilobed posteriorly, rounded 

 anteriorly. Back more or less elevated, varying from subdepressed 

 (var. a) to subcorneal (var. 7), but exhibiting all intermediate degrees 

 of convexity. The true apex is invari^^bly the highest point, from which 

 the sides decline with greater or less steepness, and anteriorly with more 

 or less straightness. The apex is always excentric, inclining towards 

 the anterior extremity. The portion of the back in front of the apex is 

 about one-sixth shorter than that behind it. The anal furrow reaches 

 quite to the apex, in some specimens slightly indenting it. It is always 

 of a lanceolate-acuminate form ; lanceolate to the upper part, the anus 

 then narrowing into a prolonged and shallower, but still strongly marked 

 groove. The anus is very deep sided, and the bounding walls of the 

 groove diverge slightly downwards. The lower part of the groove, 

 behind the anus, is very much depressed and well defined. The am- 

 f bulacra are petaloid with subparallel sides, the spaces between the rows 



* Through the kind co-operation of Mr. Woodward^ the Nucleolites of the British 

 Museum were laid out for my inspection. 



