OF WESTERN SIND. 109 



III. Description of the Fossil Uchinoidea from the Khirthar Series of Strata 



in Western Sind. 



Order -E OKI'S OlD'El A ENDOCYCLICA. 



Family CIDARID^. 

 Genus CIDAEIS, Klein, 1734. 



(See anted, p. 7, Part i.) 



Subgenus LEIOCIDARIS, Besor, 1854. 



The subgenus Leiocidaris is characterized from the true Cidaris by the conjugate 

 pores, and distinguished from Phyllacanthus, Brandt {=Bhahdocidaris, Desor) by the 

 smooth and non-crenulate tubercles. The form of the spines is also very different in 

 the last-named group of species. The character of the ambulacral area is evidently 

 one of morphological importance, v^hilst the distinction based on the tubercles and the 

 spines vi'ould seem, from the known variability of these parts in Cidaridce, to be more 

 doubtful. In his recent vcork on the Eocene Echinoidea from Egypt and the Libyan 

 Desert*, P. de Loriol maintains the genus Rhabdocidaris of Desor, and includes 

 therein (1) the species of Rhabdocidaris sensu stricto, (2) the species of Rhabdocidaris 

 with non-crenulated tubercles, (3) the species of Leiocidaris of Desor and Dames 

 amended, (4) the recent species of Phyllacanthus of A. Agassiz, and (5) the genus 

 Stephanocidaris of A. Agassiz. Although we place the greatest importance upon every 

 opinion expressed by our learned contemporary, we still consider that Brandt's genus 

 merits recognition ; and although we are far from insisting that the characters upon 

 which Leiocidaris is separated from Phyllacanthus (= Rhabdocidaris) are of any great 

 value, we regard the grouping above proposed as somewhat too sweeping in the present 

 state of our knowledge ; we therefore retain provisionally the subgenus Leiocidaris 

 rather as a useful centre around which a number of species may be grouped, than as 

 an expression of our opinion upon the morphological importance of the test-characters 

 upon which the division is based. 



1. Leiocidakis cakaliculata, Duncan & Sladen. Plate XXI, Figs. 1-9. 



Form circular, subglobular, rather high, the height being nearly three fourths of 

 the breadth (or, taking the mean of three specimens, is as 0*7 : 1 approximately). 

 Test very slightly depressed on the abactinal surface, moderately inflated at the ambitus, 

 the contraction of the test being greater below that line than above. 



Ambulacra very slightly flexuous, rather broad, contracting towards the apex, and 

 also, but in a less degree, towards the peristome. Poriferous zones deeply sunken, as 

 broad as the whole interporiferous area. Pores transversely elliptical, wide apart, 



* Palseontographica, N. F. x. 1 (xxx.). 



