504 G. T. Trechmann— 



(h) Its relation to the Rudist mollusca has been denied by 

 Whitfield, though the intermediate stages between Barrettia and 

 Hippurites are sufficiently apparent in the genera Batolites, of 

 Montfort, and Pironcea, of Meneghini. Douville has pointed out 

 that the young of Barrettia inonilifera passes through a Pironcea- 

 like stage. ^ Pironcea occurs derived in Eocene conglomerates in 

 North Italy and also in Spain and Asiatic Turkey. 



(c) Owing to Hill's reported occurrence of the commingling of 

 Cretaceous and Tertiary fossils in beds which he calls the Cambridge 

 and Catadupa formations in Jamaica, the actual Cretaceous age of 

 Barrettia and other Rudists was thrown into doubt. 



For these reasons I was particularly desirous during a recent 

 stay in Jamaica to acquire some information on these points, and 

 consequently to find the locality near Green Island where Barrettia 

 was reported to occur in quantity and presumably in good 

 preservation. In this search I was greatly assisted by two friends 

 of the Public Works Department of Jamaica, Mr. P. Martin Cooper, 

 A.M.I.C.E., and Mr. F. D. Jenoure, who kindly made exhaustive 

 inquiries for me. Mr. Jenoure found a negro who happened to have 

 watched Nicholas when he was collecting twenty-seven years ago, 

 and consequently was able to take me near the spot, as a result of 

 which I was soon able to trace the outcrop of the Barrettia lime- 

 stone. This was some days after Dr. Matley and I had spent several 

 hours of a very hot afternoon in a fruitless search for the Barrettice. 



My activities were devoted to securing a series of Barrettia in 

 various stages of growth and states of preservation, and also of the 

 large crateriform Radiolite R. nicholasi Whitfield, which was 

 reported to be the only other fossil accompanying the Barrettia 

 in this locality, and is, in fact, the only other large and con- 

 spicuous fossil. The search for other smaller accompanying fossils, 

 however, was not unsuccessful, though these, except in the case of 

 certain foraminifera, are very scarce. 



It also seemed desirable, as far as possible, to determine the 

 relation of the Barrettia limestone to the other limestones, con- 

 glomerates, shales, etc., that occur above and below it, as well as its 

 relation to the Tertiary beds, and to see if any trace of Barrettia 

 was to be found in other localities in Jamaica. 



Hitherto, except for two incomplete specimens of a species which 

 Whitfield calls Barrettia sparcilirata, recorded from Logie Green 

 on the Rio Minho, the only localities for this genus are that on the 

 Back River in Portland Parish in the extreme east, and near Green 

 Island, in Hanover Parish, in the extreme west of the island. 



I saw no trace of Barrettia in any of the other Rudist limestones in 

 Jamaica, such as that at Jerusalem Mountain in the far west ; 

 Logie Green and the Minho Valley ; the Great River Valley, including 

 the Cambridge and Catadupa railway sections ; nor in the semi- 



^ " Etudes sur les Rudistes," p. 111. 



