ECHINOIDEA. 17 



Order: lEREGULARES. 

 Suborder : GNATHOSTOMATA. 

 Family: ECEINOCONWM 

 Genus : ECHINOCONUS, Breyn. 

 EcHiNOCONTjs GiGAS, Cotteau. PL III. fig. 2-2A. 



1836. Eehinoconiit gigas, Cotteau, Paleontolt^e franfaise. Terrain Cr€t, p. 511 ; pi. 994, fig. 6, pi. 99S. 



Unfortunately only two specimens of this pretty species have been found, both 

 of which are so much damaged that I am unable to give a full description; however 

 they allow of the determination of the chief characters. 



Dimengiont. 

 Length L:=60 mm. ) 



Breadth h=5S „ > approximately. 



Height h=50 m. ) 



The test is of a subpentagonal shape, a little broader anteriorly, than 

 posteriorly, where it is visibly contracted. The upper surface is slightly inflated and 

 equally rounded in all directions ; profile line semicircular, apparently a little 

 more steeply inclined forwards than backwards. Lower surface flat or slightly 

 convex. 



Apical disc slightly excentral towards the anterior margin. 



Ambulacral areas narrowly lanceolate, extending from apex to the periproct ; 

 poriferous zones linear, slightly concav e, composed of minute pores which are 

 arranged in oblique pairs ; each pair is separated from its neighbours by a low fili- 

 form ridge, and the two pores are again separated by a vertical septum joined to 

 two horizontal ones ; each pore opens on the top of a minute boss. 



Peristome and periproct unknown. 



The ornamentation consists of small perforate tubercles, sunk in deep and 

 comparatively broad scrobicules, and very minute tubercles of the same kind arrang- 

 ed in circles round the former ; both kinds are very homogeneous and not much 

 crowded. On the interporiferous zone of the ambulacral area the tubercles are ar- 

 ranged in 6 or 7 rows, the two external ones of which are composed of smaller 

 tubercles than the others, which are of the same size. On the interambulacral areas 

 the tubercles are arranged in irregularly curved lines, in such a way that one row 

 extends from the median suture to the poriferous zones over several plates. 



Locality and stratigrapMeal position. — Mazdr Drik, horizon 8. 



Remarks. — Cotteau states that the chief specific features of Eohinoconus gigas 

 are its large size, its generally inflated test, particularly its conical transverse section. 

 Now, if we apply this characteristic to the specimens from Baluchistdn, it fits them 



