128 THE FOSSIL ECHINOIDEA 



Illustrations of the Species in Plate XXIII. 



Fig. 7. Abactinal view of tlie test : natural size. 



8. Actinal view of the test : natural size. 



9. Longitudinal profile of the test : natural size. 



10. Terminal extremity of an ambulacral petal : magnified. 



11. Apical disk : magnified. 



3, CoNOCLTPBUs EOSTKATUS, Buucan & Slaien. Plate XXIV, Figs. 1-4. 



The test is of large size, with an elongately oval marginal contour, somewhat 

 angular or protuberant in the lateral interradia, and with a comparatively prominent 

 rostration posteriorly. The greatest breadth occurs in the postero-lateral interradia, 

 and is about four fifths of the length. The anterior excentricity of the apical disk is 

 very slight ; and the greatest height of the test, which is about one half the length, is 

 placed somewhat posterior to this. Seen in longitudinal profile the dorsal outline of 

 the test is decidedly subconoidal, the anterior slope very slightly convex, and the 

 posterior slope becoming tumid in the neighbourhood of the posterior rostration and 

 terminating more or less precipitously. The outline of the transverse profile' is well 

 arched, and the margins of the test are gently rounded. The actinal surface is almost 

 fiat, slightly impressed around the peristome, and merging with a gentle slope into the 

 curvature of the margin. 



The ambulacral petals are broad, and each is situated in a faint but well-marked 

 concavity of the test, which does not terminate abruptly, but extends laterally on to the 

 interradial areas, dying out gradually. The petals remain widely open at their outer 

 extremities and terminate abruptly before the margin is reached. The width of the 

 petals is from Tb~o% to Toqo of the length of the test ; and the width of the poriferous 

 zone is very remarkable, being at its broadest part equal to, Or even slightly greater than, 

 the width of the interporiferous area, being 5 millim., or -^ of the length of the test. 

 The diminution in the width of the poriferous zone as it approaches the margin is 

 comparatively slight, and the last two or three conjugate pores diverge at an, angle from 

 the horizontal, the divergence increasing gradually in each succeeding outward pair, and in 

 this manner emphasize the abrupt termination of the poriferous zone. The width of the 

 interporiferous area at the extremity of the petal is very slightly greater than at the 

 widest part of the petal. The inner pores of the zone are round, and the outer pores 

 elongate, the pores of each pair being united by a deep furrow. The costse which 

 divide the pairs are slightly wider than the furrows and are ornamented with a single 

 line of small miliary granules, twelve to fifteen or more being present on each. The 

 ornamentation of the interporiferous area is similar in character to that of the inter- 

 radial areas, the primary tubercles being, however, rather more widely spaced. 



Peristome and surrounding portions of the test are unknown. Periproct close to 

 the posterior extremity, and (probably X) encroaching on the margin ; but unfortunately 

 the preservation of this part of the specimens at our disposal is unsatisfactory. 



B.emar1cs. A specimen which was not found in place, but is referred by the 

 collectors to the same locality, we consider to belong to this species, although it 



