OF WESTERN SIND. 269 



crenulate, showing that crenulation and size of spines and their power of movement are 

 not invariably associated. In the first-named species the bare median interradial area 

 is ornamented by a few flat, broad, inconspicuous miliaries, and by smooth broad bands, 

 somewhat raised, forming irregular S-shaped lines extending from the centre of one 

 plate to the upper edge of the following plate. These are seen more or less modified 

 and in a greater degree in the fossil forms. The arrangement of the ambulacra and 

 interradia is generally the same, but special distinctions are noticed in the recent and 

 fossil species. In the fossil forms the ambulacra are prominent, and are relatively 

 narrower than in the recent species. 



The arabulacral tubercles extend close to the radial (ocular) plates in the fossil 

 forms and also in Ccelopleurus Maillardi ; and the interference of the pairs of pores with 

 the raised scrobicules of the large tubercles is greatest in the extinct species. 



The median sutural pits near the actinal end of the ambulacra are visible in all the 

 species, but they are certainly variable in the fossil forms and most developed in the 

 recent West-Indian. They may be for sphaeridia, as Agassiz suggests in the Report 

 on the ' Challenger ' Echini. The tag-like prolongation from the peristomial cuts is 

 seen in all the species. The apical system differs, and the elliptical anal opening of the 

 East-Indian recent form is represented by an obliquely-placed oval anus in the fossil 

 species. 



The ornamentation between the large interradial tubercles and the poriferous zone 

 is diff'erent in the two fossil species, and is distinct from that of the recent forms. The 

 construction of the triplets of the ambulacral areas is shown on Plate XXXIX, Figs. 

 7 & 12. It is most singular, and characterizes the genus. Nothing resembling it has 

 hitherto been noticed. 



The study of the Gaj and Kachh forms of Coelopleurus has opened out many 

 interesting points, and we are engaged in describing the anatomy of the recent species. 

 Clypeaster simplex from the Nari series is allied to the species of Clypeaster from the 

 same geological horizon in Kachh, and its nearly equal petals are very characteristic. 



Clypeaster depressus. Sow., is common in the Nari series and in the corresponding 

 strata in Kachh, and it is therefore not a true Nummulitic form. It passes up into 

 the Miocene. 



The third species from the Nari series is not a very satisfactory one ; but the 

 humped nature of the apical area and a little beyond is characteristic. Actinally the 

 form is very concave. 



The Echinolampinae from the Nari series are very characteristic and numerous. 

 Some are very large forms indeed, and all are comparatively depressed, some very much 

 so. They differ entirely in shape from those of the Nummulitic of Kachh and from 

 those of the Miocene of that district and Kattywar. Their facies is altogether distinct 

 from that of the large Echinolampad fauna of the Khirthar Nummulitic beds of Sind, 

 where the flat, discoid, and subpentagonal forms of the Nari series have no repre- 

 sentatives whatever ; whilst, on the other hand, the elongate and regularly curved out- 

 lines of the characteristic Khirthar species stand closely distinguished from the Nari 

 species of Echinolampas. 



