ON THE GEOLOGY OF BARBADOS. 197 



*' Turning to the question of the probable depth at which these 

 beds were deposited, the evidence still leaves a good deal to be 

 desired. It is generally assumed that the presence of skeletons of 

 radiolaria and similar siliceous remains as the chief constituents of 

 a deposit is an indication that it was laid down at a considerable 

 depth, and the ' Challenger ' researches give a general support to 

 this view. I have notes of 41 ' Challenger ' bottom dredgings more 

 or less characterized by abundance of radiolaria, and of these only 7 

 were taken at a depth less than 1000 fathoms, whilst 25 were from 

 more than 2000 fathoms. On the other hand, the almost complete 

 absence of the pelagic varieties of Pulvinulina, and, except in the 

 Eissex Hill material, the poor show of Globi(/erince, whilst certain 

 other calcareous forms are well represented, are not what one would 

 expect in a deep oceanic deposit far from land/ 



"The annexed table (p. 198) furnishes us with ten or eleven 

 salient species, whose known distribution in the living condition is of 

 value as far as it goes. 



" Miliolina venusta was found at 12 ' Challenger ' stations, ranging 

 from 1070 to 2750 fathoms, and at only one in shallow water, and 

 though it has since been recorded from some other shallow-water 

 localities it may be considered relatively as one of the deep-water 

 forms of Miliolidce. 



" Verneuilina triquetra, in 'ChaUenger ' material from 390 fathoms 

 (West Indies), 210 fathoms (Pacific Islands). 



^^ Pleurostomella subnodosa, at 1825, 2200, and 2350 fathoms. 

 „ hrevis, at 129 and 1950 fathoms. 



„ aliernans, at 129 and 2075 fathoms. 



" Cassidulina subglobosa, at 50 stations, 6 of which have a depth 

 of more than 2000 fathoms, 17 of more than 1000, 23 of more than 

 400, while 3 are under 100 fathoms. 



"• AllomorpTiina trigona, recent at two stations only, 345 and 620 

 fathoms. 



"• PolymorjpTiina angusta, at 14 stations, 7 of which have a depth 

 of more than 2000 fathoms and ouly 3 of less than 1000. 



" Rotalia Soldanii, at 57 stations, of which 41 are from depths of 

 more than 1000 fathoms. 



" Nodosaria hisj>ida, var. sublineata, 435 fathoms (West Indies) 

 and 350 fathoms (Pernambuco). 



" As I have already stated, a more complete examination of these 

 rocks and their constituent organisms should throw into much 

 clearer light the points under consideration. The aspect of the 

 rhizopod fauna apart from the species just referred to, without being 



^ We now know that the Globigerina-ma,vls and limestones of Bissex Hill are 

 at least 50 feet thick, and that in this locality there is a fine show of Globi- 

 gerincB. A sample from one of the limestone-blocks was afterwards sent to 

 Dr. Brady, who wrote to us as follows: — 'The limestone of which it is a 

 section exactly resembles a modern sea-bottom of, say, perhaps 1000 fathoms 

 (more or less), formed, at any rate, in open ocean, away from land influences, 

 fi'rom a section one always has to speak with a margin, as it is next to impos- 

 sible in many cases to identify species. Still, I do not think at 1000 fathoms 

 you will be very far wrong.' 



