OF KACHH AND KATTYWAR. 



57 



rounding the anal space, composed of five prominent genital and five ocular plates, all 

 perforated and alternating ; one of the former combined with a madreporiform tubercle. 

 Ambulacral avenues composed of pairs of pores indistinctly ranked, their ranks con- 

 fluent throughout. Spines of one order." 



By omitting the family peculiarities we might diagnose the genus as : — Spherical or 

 tumid turban-shaped Urchins, Apical system well developed and regular ; peristome 

 small, sunken, with very small cuts ; ambulacral pores nearly straight in series ; transverse 

 sutures of ambulacra and interradia with fossettes. Tubercles non-crenulate and imper- 

 forate. The negative characters are the absence of true pits along or at the ends of 

 sutures, and the absence of obliquity in the apical system. Occasionally a crenulated 

 tubercle is seen. 



Temnechinus, thus restored, difiers from Temnopleurus and its subgenus Pleurechinus, 

 for these have true pits at the angles of plates which undermine the test, and are accom- 

 panied by a knob-and-socket jointing of the plates. 



In Dictyopleurus (Foss. Echin. of Western Sind, p. 38) the apical system is 

 oblique and an ocular plate enters the ring ; the pores are continuous in series, and 

 the ornamentation is of raised zigzag ridges narrow or broad ; there are no true sutural 

 pits ; tubercles crenulate and perforate. 



Arachniopleurus has a costulate ornamentation peculiar to itself, and no true pits. 



Gemis TEMNECHINUS, Forhes, 1852. 



1. Temnechinus Roussbaui, d'Archiac, sp. Plate XI, Figs. 7-11. 



The species remarked on above, which is so characteristic of the Kachh Miocene. 

 Locality. North of Akri, south of Bair. Miocene series. Survey-numbers C 054, 

 C 054 A f. 



Illustrations of the Species in Plate XI. 



Fig. 7. The test : natural size. 



8. The apical system : magnified. 



9. Part of an interambulacrum and a poriferous zone : magnified. 



10. Part of a worn ambulacrum : magnified. 



11. Part of a perfect ambulacrum : magnified. 



Amongst the specimens of this species are several which, although quite as large 

 as the type, have only slight traces of sutural fossettes, or do not have them at all. 

 The rest of the ornamentation is the same as in the type. 



Plates without fossettes. 



Plates with slight fossettes. 



