ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 911 



considerable percentage (6 to 10) of silica has been established as 

 existing in the arenaceous forms. The substance secreted for the 

 incorporation of the foreign bodies which cover the test has been 

 proved to be composed of ferric oxide and carbonate of lime in 

 variable proportions, the former being often in considerable excess. 

 It is not without interest to note the presence in some of the porcel- 

 lanous forms of a thin siliceous investment. A few Miliolce from 

 soundings of a depth of about four and a half miles, with somewhat 

 inflated segments, scarcely distinguishable in form from young thin- 

 shelled specimens of a common littoral species, were found to be 

 unaffected by treatment with acids, and upon further examination it 

 became apparent that the normal calcareous shell had given place to 

 a delicate homogeneous siliceous investment. While immersed in 

 fluid, the shell-wall had the appearance of a nearly transparent film, 

 and this when dried was at first somewhat iridescent. 



A list is given of those stations from which soundings or dredgings 

 were obtained in sufficient quantity to furnish good representative 

 series of Rhizopods, and maps are appended showing the tracks of the 

 ' Challenger,' with these stations marked, as also of the areas 

 ex2>lored by the ' Porcupine ' and other northern expeditions. 



Any generalized summary of the details of the new forms would 

 be impossible. Of the several hundred species described and figured, 

 over eighty are hero noted for the first time, and this without count- 

 ing numerous well-marked and named varieties, or the numerous new 

 forms already diagnosed in Mr. Brady's preliminary reports. 



The family Astrorhizidas is the one which has received the largest 

 number of additions ; indeed our acquaintance with the larger 

 arenaceous Ehizopods is almost entirely derived from the various 

 recent deep-sea explorations. A knowledge of the life-history of 

 these forms is still needed to place the classification of the group on 

 a secure basis, and as some few of the forms are inhabitants of com- 

 paratively shallow water, their investigation would seem to be well 

 worthy of the attention of observers at some of our zoological marine 

 stations. Many other problems to be solved are also pointed out in 

 this report, the extreme value of which will bo recognized by all 

 students of biology.* 



Copulation in DiflBlugia globulosa.f— But few observations have 

 been recorded on the copulation and conjugation of Ehizopoda. An 

 instance of this phenomenon has been studied by Dr. C F. Jickeli 

 who gives the following description of it. Two examples of D. glo- 

 hulosa, one distinguishable by the greater transparency of its shell, 

 were observed to attach themselves together by the mouth aperture ; 

 from this point four long and mobile pscudopodia extended themselves ; 

 in 24 hours the animals were still firmly attached, but the pseudopodia 

 had vanished ; after the lapse of another 24 hours the shells had become 

 detached. On investigating the two by means of reagents, it was 

 found that the shell of the individual formerly recognizable by its 



* Nature, xxx. (1884) pp. 533- i. 



t Zool. Anzcig., vii. (1884) pp. 449-51. 



