On the Biluchi Tribes inhabiting Sindh. 395 



limestone, and the older coal measures. Others occupy a re- 

 latively circumscribed area, yet none are called formations 

 which are not the products of distinct formative actions ope- 

 rating during epochs characterised by distinct groups of races. 

 My brief limits will not allow me to present here even the 

 general scheme of names by which we purpose to designate the 

 divisions of this extensive system of strata ; but T will explain 

 succinctly the principles upon which the names are chosen. 

 The title given to any formation is composed, first, of the 

 name of the period to which it appertains ; and, secondly, of a 

 word or words descriptive of the ruling mineral character of 

 the rock ; and to these is appended, when we wish to specify 

 the type under which the formation is referred to, the name 

 of the district or place where it is so developed. Let me ex- 

 emplify this by one or two instances. The well characterized 

 formation, called in the New York survey, the Marcellus 

 shales, is named by us the Postmedidial older black slate, while 

 the Genesee slate is called Postmedidial nev-er black slate, and 

 a member of the Clinton group of New York, occurring there 

 as a thin bed of brown and ponderous sandstone (seen on the 

 Sequoit), but expanded in Pennsylvania and Virginia into an 

 important mass, having characteristic fossils, and a maximum 

 thickness of two hundred feet, we propose to call the Levant 

 iron sandstone. — American Journal of Science and Arts, Vol. 

 xlvii.— No. 1, p. 154, July 1844. 



On the Biluchi Tribes inhabiting Sindh in the Lower Valley of 

 the Indus and CutcU. By Captain T. Postans.* 



Communicated by the Ethnological Society, 



The general term of Biluchi is applied to a race professing 

 the Mahomedan religion, whose country is hence called 

 Biluchistan, which may be described as the whole of that 

 mountainous and desert region stretching westward of the 

 Indus from Cape Monze to the Valley of Shawl, and of which 

 Kelat may be considered as the capital. This people thus 

 form a connecting link, as it were, between the Persian and 



* Read before the Ethnological Society on the 10th of April 1844. 



