474 Mr. H. J. Carter on Deep-sea 



favour of the XantJiidia being the petrified orbicular stato- 

 blasts of the Polyzoa than the petrified sporangia of Desmi- 

 dieee." 



Xanthidiwn hicirratum^ n. sp. (PI. XV. fig. 44.) 



General form a spheroidal or slightly elliptical cell, provided 

 with two opposite erect cirri, each of which, after a short 

 distance, divides into two longer filaments that, recurving in 

 opposite directions apparently in the same plane, finally cross 

 those of the opposite side. Cell empty or filled with a few 

 yellowish fragments of soft material. Composition chitinous. 

 Size of cell about 2-6000ths inch in diameter; length of 

 cirrus before dividing about 1 -6000th inch, length of filaments 

 after dividing 5-6000ths inch. 



Hob. Marine. 



Loc. Common between the north of Scotland and the Faroe 

 Islands. 



Ohs. Although, in this instance, the cell is not more than a 

 fifth of the size of that of X. ahyssorum, its general appearance, 

 together with its contents, inclines me to view it as a Xantlii- 

 dimiv — that is, the shell, at least, of the e^g of a Polyzoon. 

 Nitric acid applied on the slide does not cause any apj)reciable 

 alteration in the shape, nor does drying or mounting in balsam, 

 probably on account of the chitinous wall being thicker than 

 in X. ahyssormn. 



Coccoliths and Rhabdoliths. 



The oval and cyclical Coccoliths with their respective Coc- 

 cosylieres have also been generally present in great abundance; 

 also Mliabdoliths^ but no Rhabdosj)heres. The oval CoccoUth 

 appears to abound between the north of Scotland and the 

 Faroe Islands ; the cyclical one southwards, and the Rhahdo- 

 liths from the " chops of the English Channel" to Cape St. 

 Vincent, where all three forms are found together — at least, 

 judging from what I have observed about the sponges from 

 these three different localities. 



I might here add that, in the sand about the sponges in the 

 British Museum, dredged up by Sir J. Ross in 300 fathoms, 

 74|°, and in 206 fathoms, 77|° south latitude, respectively, 

 I found no Coccoliths and very few Glohigerince^ but many 

 Radiolaria. 



Black Geains. 



Among the Glohigeriniferous sand may often be observed 

 " black grains," frequently shapeless and more or less angular, 



