64 THE FOSSIL ECHINOIDEA 



Subfamily EGHINANTHIN^. 



Genus ECHINANTHUS, Breynius. 



1. EcHiNANTHDS ENORMis, sp. nov. Plate XVII, Figs. 5-10. 



The test is tumid, irregularly hemispherical, higher in front than behind, longer 

 than broad, and stands on a small base, which is overhung by the swollen margins. 

 The marginal outline is elliptical and broadest centrally, rounded in front, and very 

 faintly marked by a groove posteriorly in the median line. The test is faintly swollen 

 and convex actinaliy. The highest point of the test is eccentric in front ; thence it 

 slopes rapidly, the anterior longitudinal section being nearly semicircular ; behind the 

 slope is gradual and longer to the slightly projecting edge above the periproct. From 

 the periproct, which is rather high up, there is an oblique truncation, so that the 

 test passes from the posterior margin upwards and backwards. On either side of the 

 apex the slope is less convex, so that a conical appearance is given in section. 



The apical system is very eccentric in front ; and the disk corresponds with the 

 highest point of the test ; there are four generative pores ; and the madreporic body 

 is small and central. 



The anterior odd ambulacrum is dwarfed and very short, it is open and narrow ; 

 the poriferous zones are short; and indifferent specimens there are from 8 to 15 pairs 

 of pores in each zone, which are conjugate. It reaches but a short distance down 

 the rapid anterior slope ; and then the inner row of each poriferous zone is continued in 

 single series, which gradually widen apart to the margin, over which they pass to the 

 peristome. 



The antero-lateral ambulacra are well developed, form a large angle, are petaloid, 

 moderately open, and have broad interporiferous zones. The poriferous zones are rather 

 narrow ; and the subcircular large pores are conjugate, with well-marked ridges between 

 the pairs. 



The postero-lateral ambulacra are the longest, form an acute angle, and reach to 

 within their own length of the posterior truncation. Narrower than the antero-lateral 

 pair, more lanceolate, and more open, they are broadest near their inner third. 



The interambulacra are largely developed on account of the smallness of the 

 abactinal rosette, and the posterior one is marked by a very faint rounded keel leading 

 to the periproct. The ornamentation is of small tubercles in shallow sunken scrobicules, 

 and it is rather close. 



Actinaliy the test is slightly convex ; and the peristome is small, excentric in front, 

 pentagonal, longest transversely (in some specimens the longitudinal axis of the 

 peristome is not quite in the median line). The floscelle is moderately developed ; the 

 bourrelets are slightly tumid and project downwards ; and the phyllodes are open distally, 

 are short, and have a few double pores. 



The ornamentation of the actinal surface resembles that of the abactinal ; and here 

 and there minute granules encircle the scrobicules, and others are on the intermediate 

 parts of the test. 



