12 THE FOSSIL ECHINOIDEA 



to be subpentagonal in shape ; but, owing to the condition of the specimen, it is 

 impossible to determine with accuracy the details of the form and structure of this and 

 the adjacent parts of the test. There appears to have been no development of the 

 peristomial interambulacral plates (bourreiets), although it is probable that a rudi- 

 mentary floscelle was formed by the small incipient phyllodes above referred to. 



The periproct is large, elongate, oval or subpyriform, the long axis placed longi- 

 tudinally, half on the margin and half on the actinal surface of the test, quite 

 invisible from above, and overarched by the slight posterior rostration of the odd 

 posterior interradium. It measures about one quarter of an inch in length, and is much 

 larger than the mouth. Too great importance, however, must not be placed upon the 

 actual measurement, as the margin of the aperture has been to a certain degree 

 modified by damage, either previous to fossilization, or during the process of clearing 

 from the matrix when found. 



Dimensions. Length of the specimen 1^ inch ; breadth 1^ inch ; height 

 I inch. 



Distance of apical system from posterior edge yo inch. 



Locality. Below Jakhmari peak, Laki range, west of Amri. Survey-number 



n 2.80 



Illustrations of the Species in Plate I. 



Fig. 8. Abactinal aspect of the test : natural size. 

 9. Actinal aspect of the test : natural size. 



10. Outline of the longitudinal profile of the test. 



11. Outline of the transverse profile of the test. 



12. Apical system : magnified. 



13. A portion of the ambulacral and interambulacral areas : magnified. 



14. Part of an ambulacrum near the peristome: magnified. 



15. Tubercles on the abactinal surface : magnified. 



16. Tubercles near the ambitus : magnified. 



Genus ECHINANTHUS, Breynius, 1732. 



Test oval, elongate, subdepressed, more or less convex above, and slightly concave 

 below ; margins tumid. 



Ambulacra petaloid ; petals short, unequal, widely open at their extremity. Pori- 

 ferous zones subequal, with pores round or oblong ; pairs conjugate, united by a groove. 



Apical disk compact, excentric in front. 



Peristome subpentagonal, more or less excentric in front; floscelle more or less 

 developed. 



Periproct oval, often vertically elongate, marginal or supramarginal, placed at the 

 summit of a more or less well-developed groove. 



Tubercles small, crowded, perforate, non-crenulate, sunken in a deep scrobicule ; 

 miliary granulation more or less compact. 



