T02 NATURAL SCIENCE. Feb.. 



including five from the Indian Ocean^, taken at depths of 1,040 

 fathoms, 1,277 fathoms, 2,190 fathoms, 2,550 fathoms, and 2,694 

 fathoms respectively. From these five soundings we have obtained 

 thirty-one species of arenaceous Foraminifera. Of these, only four 

 are found in the first two soundings named, while thirty species 

 occur in the remainder, the richest sounding being the deepest. The 

 increase of arenaceous Foraminifera with depth is also strikingly 

 shown in two soundings which we have recently examined from 

 Torres Straits, about seventy miles east of Raine Island.- The first 

 sounding, at a depth of 790 fathoms, yielded ten arenaceous species ; 

 the second, at a depth of 985 fathoms, yielded twenty species, includ- 

 ing such coarse varieties as Verneuilina propinqiia, Reophax nodnlosa, 

 Haplophvagmium latidorsatum, and H. glohigerini forme. 



In connection with the distribution of arenaceous Foraminifera, 

 we may here remark that Messrs. Balkwill and Wright, in their 

 paper on Recent Foraminifera from the Irish Sea, 3 have shown in a 

 striking manner that arenaceous Foraminifera, while very common on 

 muddy bottoms, are rarer on bottoms composed of mud with sand, 

 and are absent from bottoms consisting of pure sand. Our own 

 examination of the soundings already quoted also goes to show that 

 the arenaceous Foraminifera flourish on bottoms which contain little 

 or no admixture of free sand-grains. 



We now proceed to consider in greater detail the evidence 

 brought forward by Mr. Hume. He states : " Those species which 

 are restricted to the Chalk Marl and Lower Grey Chalk are those 

 which occur to-day at depths of less than 400 fathoms. "+ In support 

 of this statement he cites Textilaria tiivris, T. tvochus, T. agghitinans, 

 Gaudryina pnpoides, Bnlimina presli, Haplophragmium latidorsatum, Ammo- 

 discus incertus, Tritaxia tricarinata, Spiroplecta annectens, Gaudryina rugosa, 

 and Froiidicularia avchiaciana. 



I. Much stress is laid upon the occurrence of the three species 

 of Textilaria together at the same spot, viz., off Culebra Island. We 

 cannot, however, think that much importance should be attached to 

 this. T. agghitinans occurs in all seas and at all depths, and probably 

 few soundings could be taken without finding a specimen. T. tuvris 

 and T. trochus are species very closely allied to each other, if, indeed, 

 they are not mere varieties of the same form. T. trochus, the 

 ■depressed and more common of the two, is plentiful in the shallow 

 waters of many tropical and subtropical seas, and is by no means 

 confined to localities having the peculiar position assigned by Mr. 



^The exact localities are {a) lat. 6""" 37' 15" N., long. 79° 26' 21" E. 



(b) „ 6° 25' 47" N.. .. 79° 24' 14" E. 

 {c) „ 2° 13' 30" S., .. 44° 13' 00" E. 



[d) „ 2° 20' 03" S.. „ 46' 3' 06" E. 



[e) ,. 2° 47' 12" S.. .. 47° 39' 45" E. 

 ■^The exact localities are (a) lat. 11° 16' 7" S., long. 145° 14' E. 



(b) ,, 11^ 07' 6" S.. .. 146° 39' E. 

 ^ Trans. Roy. Irish Acad., xxviii., pp. 317 et sqq. ; 1885. 

 ^Nat. Sci., vii., p. 274 ; Oct., 1895. 



