16 THE FOSSIL ECHINOIDEA 



known forms. E. testudinarius, Desor, and B. Biarritzensis, Cotteau, are, perhaps, the 

 nearest related. Compared with E. testudinarius, the keeled and elevated posterior 

 interambulacrum, the greater height posteriorly of the test, the greater length and the 

 smaller angle of divergence of the posterior petals, as well as the general shape of the 

 ambulacra and the different character of the posterior extremity in the new form are 

 distinctive. From E. Biarritzensis the Sindian species is well marked by its more 

 broadly oval contour, with no trace of rostration posteriorly, by its greater depression, 

 by its much narrower and smaller ambulacral petals, and by its elongately ovate 

 periproct. 



The nature of the posterior truncation, the absence of a projection posteriorly 

 beneath the periproct, and, more important still, the character of the ambulacra and 

 of the peristome separate the species from Cassidulus as a genus. 



The absence of the longitudinal smooth band between the mouth and the 

 periproct, the outline of the posterior portion of the test, and the vertical position of 

 the periproct distinguish the species from members of the genus PygorJiynchus. In 

 some specimens, however, a slight median smooth space occurs along the median line 

 of the posterior interradium ; but this is in all probability only the result of wearing, 

 as tubercles are present in well-preserved specimens. 



The species above described is not comparable with any form of Echinolampas, 

 the position of the periproct, its longitudinal elongation, the simplicity and equality of 

 the ambulacra, and the well-developed floscelle readily remove our form from that 

 genus. Neither is it comparable with the Bhynchopygus, Botriopygus, Nucleolites, or 

 Echinobrissus of palaeontologists. 



Leaving out the details of structure enumerated above, which clearly determine 

 the generic position of this species, the form may be said to recall in a general way 

 some of the characters of Catopygus and Echinolampas — this, however, suggestively 

 rather than in reality. 



Dimensions. The following are the measurements of three of the largest spe- 

 cimens : — 



Length 1-^ inch, -^ inch, 1 inch. 

 Breadth -^o inch, -^^ inch, xo inch. 

 Height -Yo inch, -yq inch, ^ inch. 



Locality. Barki nala, hills north of Eanikot, Laki range. Survey-number G ff §. 



Illustrations of the Species in Plates II & III. 



Plate II. 



Fig. 1. Actinal aspect of the test: natural size. 



2. Abactinal aspect of the test : natural size. 



3. Profile view of the test, showing the posterior extremity : natural size. 



4. Outline of the transverse profile of the test. 



5. Apical system : magnified. 



