200 THE FOSSIL ECHINOIDEA 



Locality. In the Khirthar series of strata. On the road about four miles west of 

 Kotri. Survey-number -^^. 



Elustrations of the Species in Plate XXXIV. 



< Fig. 12. Abactinal view of the test : natural size. 



13. Portion of the odd anterior ambulacrum : magnified. 



14. Portion of one of the antero-lateral petals : magnified. 



4. Hbmiastbk digomjs, d'ArcUac, sp. Plate XXXV, Figs. 4-9. 



This small and well-characterized form is very numerous in the white chalky saline 

 limestone, on the Baran river, near Kotri. Although the collection contains a great 

 number of specimens the largest does not exceed 22 millim. in length ; and owing 

 either to considerable decay prior to fossilization, or more probably to some chemical 

 action induced by the nature of the deposit, comparatively little structure is preserved, 

 notwithstanding that the specimens at first sight appear to come well from the matrix 

 and would be taken for well-preserved examples. 



We are fortunately able to add to the description given by MM. d'Archiac and 

 Haime (op. cit. p. 220) a notice of the peripetalous fasciole, which we have succeeded 

 in tracing in several examples completely, and more or less so in the majority of 

 specimens before us. It is, however, very indistinct and difficult to make out. Its 

 course is very rotund, devoid of any reentering sinuosities, and it passes at a low 

 level anteriorly across the anterior sulcus. Its relation to the petaloid ambulacra is 

 shown in fig. 7. 



In general form this species presents considerable resemblance to that of Schi- 

 zaster thebensis, de Loriol ; the resemblance, however, being only so far as the character 

 of the outline is concerned. 



In examining a large series of specimens, it seems to us that the form of the 

 test is generally more inflated at the sides and higher in the odd posterior inter- 

 radium than in the figures given of this species in the ' Animaux fossiles.' There is, 

 however, a considerable amount of variation in this. Considerable variation also exists 

 in the degree of the posterior excentricity of the apical disk and likewise in the 

 width of the anterior groove. We have drawn in fig. 8 an example in which the 

 groove of the odd anterior ambulacrum is remarkably wide and trough-like, the inner 

 portion of the anterior interradia being reduced to high angular keels. Fig. 9 shows 

 a small example in which the apical disk is pushed backward to an extreme degree, 

 the small posterior petals appearing, when seen from above, to be situated on the 

 sloping curve of the posterior extremity. 



Localities. In the Khirthar series : — 



i. Bolari Bridge, on the Baran rivers, south-west of Kotri. Survey-number 2_?§2_ 



ii. Three or four miles south-south-east of Meting. Survey-number ^^. (A single 

 badly preserved specimen.) 



