OF WESTERN SIND. 205 



and thence sweeps round the antero-lateral petal with a well-rounded curve ; the 

 course then curves with a re-entering sweep across the lateral interradia and runs 

 nearly parallel with the median longitudinal line of the test until it is abruptly 

 rounded at the extremity of the postero-lateral petal, and thence proceeds at right angles 

 to its previous course across the odd posterior interradium. 



The subanal fasciole is large, reniform, and bounds the subanal plastron; its 

 incurved margin forms the line of separation between the vertical posterior extremity 

 and the inclined subanal plastron, whilst the adoral or convex margin separates the 

 subanal and the actinal plastron, the deepest part of the curve passing through the culmi- 

 nating point or peak of the actinal longitudinal ridge. Three or four pairs of ambu- 

 lacral pores are included within the fasciole on either side of the subanal plastron. 



The ornamentation of the test consists of large primary tubercles having a small 

 perforate mamelon on a large, button-shaped, and granularly crenulated boss, placed 

 on a circular disk-like scrobicule ; and with a few minute and uniform granules irregu- 

 larly dispersed between neighbouring scrobicules. The primary tubercles are very small 

 on the abactinal surface generally, but are large on the actinal surface, especially on 

 the anterior part of the test and at the margin. In these regions it not unfrequently 

 happens that one edge of the scrobicular disk is raised, forpaing a small semicircular 

 embankment, the remaining portion of the disk being apparently aborted. 



BemarJcs. The nearest ally of this species is probably Brissopsis Jimenoi, Cotteau, 

 from the Miocene of Cuba. The Indian species, however, is readily distinguished by 

 its more elongate and more depressed form, by its anteriorly excentric apical disk, by 

 the different form of the peripetalous fasciole, and by the prominent and peak-like 

 culminating point of the actinal plastron. 



The form appears to be very constant, and young examples 18 millim. in length 

 have a,ll the characters of the adult stage. The test, however, is relatively narrower 

 and more elongate in small specimens, and the greatest breadth is near the anterior 

 extremity, and the posterior portion of the test is more contracted than in the larger 

 specimens. The latter embryonic character is most marked in the smallest example we 

 have, which measures 12 millim. in length. 



Length of the test . . 

 Breadth of the test . 

 Height of the test . . . 



Locality. In the Khirthar series of strata. Lowest scarp under Karothur hill, 

 eight miles east-north-east of JTungshahi (at the base of the group). Survey-number 



G280 

 118 • 



Illustrations of the Species in Plate XXXV. 



Fig. 17. Abactiaal view of the test : natural size. 

 1 8. Actinal view of the test : natural size. 



2e 



