54 THE TERTIARY FOSSIL ECHINOIDEA 



having been large and prominent on either side. Small ridges and grooves radiate 

 from the bunch right and left, and some pass over onto the ocular plates. The angular 

 part of the plate is free from these ridges ; but a curved groove, convexity upwards, 

 intersects the plate on a level with the generative pore. 



This species occurs in Kattywar, and its details will be more carefully considered 

 in treating of the fossils of that locality. 



Illustration of the Species in Plate XII. 

 Fig. 1. Part of the test: magnified. 



Fawvily GLYPHOSTOMATA. 



Subfamily TEMNOPLEUBID^. 



Numerous specimens of the beautiful Echinoid which was described and figured 

 by MM. d'Archiac and Haime* as Temnopleurus Rousseaui, d'Archiac, occur in the 

 Arenaceous or Miocene deposits of Kachh north of Akri, south of Bair. They are 

 often so well preserved that many of the structural peculiarities which are not visible 

 in the very unsatisfactory types in the museum of the Geological Society are readily 

 studied ; for instance, the apical system and the peristome. Some of the specimens 

 are worn ; and this enables us to compare the sutures of the coronal plates with those 

 of Temnopleurus toreumaticus from the present Indian Sea. The structure of the 

 ambulacral plates is visible in some worn specimens ; and it is clear that the statement 

 made by MM. d'Archiac and Haime that each plate is pierced externally by three pairs 

 of pores is incorrect. The plate is really composed of three, two large and one accessory, 

 and each of these is perforated by a pair of pores. The first two enter into the composi- 

 tion of the plate beneath the ornamentation, across which, however, the sutures run ; 

 and the third is a small plate not entering much into the composition of the plate 

 proper. 



The pair of pores are close, and in some places the usual slight curving of triplets 

 is not seen. 



The fossettes along the horizontal sutures are, as stated by MM. d'Archiac and 

 Haime, " peu profonde" and broad, and nearly as long as broad. We notice that 

 the suture is seen at the bottom of the fossette, and that this state diff-ers in the same 

 specimen actmally and abactinally and at difi'erent stages of growth-the young and 

 old forms having very differently shaped and ornamented ambulacra. In some sped- 

 mens the zigzag median line of the ambulacra is very visible, in others it is much less 

 so. Each plate has a large tubercle on it near the poriferous zone, and closer to the 

 actinal than the abactinal transverse suture. A smaller tubercle is close to the angle 

 of the plate near the median zigzag line, and three miliaries are above the larger one, 



* Op. cit. p. 205, pi. xiii, fig. 10. 



