208 



THE FOSSIL ECHINOIDEA 



with the flat actinal surface, present a facies widely different from that of £rissojpsis. 

 The character of the ambulacral petals is difierent ; and the form of the peripetalous 

 fasciole appears to be more simple. The drawings of the species given in the ' Animaux 

 fossiles ' are not good, and appear to have misled Desor to place the form in the 

 genus Prenaster, an error which has been subsequently repeated by de Loriol. 



Variations. In examining a large number of specimens from difierent localities a 

 considerable amount of variation may be observed. This chiefly affects the form of 

 the test only ; and although the modified characters may possibly have, to a certain 

 extent, a local significance, we do not consider that they demand any further recognition 

 than a notice of their occurrence, as intermediate connecting-links with a central type- 

 form may readily be traced. The extremes of this range of variations may be said to 

 be : — (1) a form in which the breadth is greater and the height is less in proportion 

 to the length of the test than in the central type — the result being a comparatively 

 depressed and more rotundly oval form ; and (2) a form in which these proportions are 

 reversed, the breadth being less and the height being greater in relation to the length, 

 the general aspect of the test being consequently more elongate, with the abactinal 

 surface higher and more arched or subconoid in character when seen in profile. The 

 wider and more rotund variety is usually of larger size, and appears to be abundant at 



the collecting-stations designated with the Survey-numbers ^-fg- and -jjj^, whilst the 

 more elongate and higher form seems to be best represented at station -gg-. 



Length of the test 

 Breadth of the test 

 Height of the test 



G280 



111c 



millim. 



. 34 

 . 31-5 

 . 19-5 



, G280 

 miUim. 



34 

 30-'5 

 ,15-5 



d^ 



Dimensions. 



G280 

 millim. 



32-5 

 30-O 

 15 



G280 



118 

 millim. 



32-5 



28-5 

 15 



0-280 

 ^- lUc' 

 millim. 



30 

 26 

 17 



/• 



a280 

 96 

 millim. 



24-5 



22 



14 



G280 

 5'- -96- 

 millim. 



17 

 14 



8-75 



Localities. In the Khirtbar series of strata: — 



i. Lowest scarp under Karothur hill, eight miles east-north-east of Jungshahi (at 

 the base of the group). Survey-number 



118 



G280 



ii. East of Jungshahi. Survey-number jj,j, . 



iii. Three or four miles south-south-east of Meting (at base of the scarp). Survey- 



number 



G280 

 111c" 



iv. Five miles east-fifteen-north of Ghatana Trig Station, near Jhimpir. Survey- 

 number ^. 



106 



GI-280 



G(-280 



v. Aongar hill scarp, east of Meting E-ailway-Stationo Survey-number -gg-. 



vi. Limestone ridge, three or four miles south of Band Vero. Survey-number 



vii. North by east of Meting. Survey-number 



a 280 



