OF WESTERN SIND. 243 



of P. serrata might probably be owing to wearing and attrition during the process of 

 fossiliz9,1;ion, an opinion which we are fully disposed to endorse. 



The 62 undoubted Khirthar forms of irregular Echini belong to 20 genera. The 

 presence of Amhlypygus, EcUnolampas, Brissopsis, Metalia, Macropneiistes, and Uuspa- 

 tangus imparts a strikingly marked and characteristic facies to the fauna. 



The genus Conodypeus is represented by four well-marked species, and the only 

 other gnathostomatous exocycloid Echinoids in the collection are the diminutive genera 

 Sismondia and Eckinocyamus, the Khirthar species of which exhibit an extraordinary 

 amount of variability. 



The Cassidulidse are present in great force. Oi Amblypygus there are four species, 

 one of which serves well as the representative of the European A. dilatatus. From the 

 series of specimens at our disposal we have been enabled to study the structural pecu- 

 liarities of the genus, and have indicated that its association with the Echinoneince 

 becomes necessary. 



The interesting little forms to which we first gave the name of Eolampas in the 

 Ranikot series, where they appeared to stand as the forerunners of the genus Echino- 

 lampas, are represented by a distinct species in the Khirthar strata. 



The genus EcMnolampas now becomes a dominant form, and no less than eleven 

 distinct species and a variety are recorded in the preceding pages. All of these, as a 

 whole, have a decided and characteristic facies distinguished by the comparatively low 

 test and the usually narrow and slightly expanded ambulacral petals. One of the 

 species presents features which show close alliance to E. discoideus, and another has 

 affinities with the forms of which E. Escheri and E. subcylindricus are the represen- 

 tatives ; a third is very nearly related to the E. dlensis of the Swiss Nummulitic strata, 

 and this species shows perhaps a closer alliance to the European form than any other 

 Khirthar Echinoid. There is also a form, represented only by a single example, which 

 is very near to E. Jacquemonti, an abundant species in a higher horizon. 



Echinanthus is represented by a very unsatisfactory specimen ; but its near ally 

 Ilarionia occurs plentifully. The Indian species of the latter genus shows considerable 

 variation in form, and the characters upon which the genus was established are also 

 somewhat modified. 



The single species of Cassidulus is distinct from, but representative of, the species 

 in the Ranikot series. 



Hhynchopygus is a common form in the Khirthar strata, and its two species here 

 take the place of Eurhodia, which is characteristic of the Ranikot beds. The small 

 species B. pygmceus, which was noticed in the description of the Ranikot Echini, was 

 probably included in that collection by mistake; and the evidence upon which this 

 assumption is based will be referred to presently. The species is numerously repre- 

 sented in the Khirthar series. 



One of the most interesting forms in the collection has been referred by us to the 

 genus Micraster, although its form is more or less abnormal in comparison with the 

 general character of that group, the test being high, tumid, subglobose, and very 

 slightly indented by the anteal sulcus ; its structural details, however, appear, as far as 



