Alcide d'Orhigny. 25 



absolutely staggering. It is as follows : " Tbe Cephalopoda of 

 this Order have a bursiform body, in the posterior portion of 

 which the shell is enclosed ; this body is sometimes of great 

 volume compared with that of the head, to which it serves as a 

 refuge in moments of danger, enclosing it almost entirely in the 

 anterior folds of the skin. This head is very small, slightly, or 

 not at all, distinct from the body, and terminated by numerous 

 tentacles, which are disposed in several rows round the mouth, 

 which is central." At such a description of a Foraminifer as 

 this the brain of the modern Khizopodist reels, and his senses 

 gape! 



He then calls attention to the fact that certain species are 

 sessile or attached, in which case the shell is separated from its 

 host by " a portion of the ' sac ' which is interposed between the 

 shell and the foreign body which serves it as a support. This 

 privation of locomotion leads us to presume that in these Mollusca 

 the two sexes are combined in the same individual." 



It seemed to d'Orbigny that the attachment of the body to the 

 shell was slight, that when it is touched after death it separates 

 from it, decomposing rapidly, leaving only in the shell a coloured 

 liquor which fills all the cavities of the chambers, the colour- 

 density increasing from the first to the last chamber. D'Orbigny 

 clearly gathered this from the vast masses of Nonionina depressula 

 (F. & M.), which compose 99*9 p.c. of the Foraminifera of 

 Esnandes. A large proportion of tliese shells, which are extremely 

 hyaline, are found, in the dried material, to be full of dark orange 

 protoplasm, and I observed on the spot that whole patches of the 

 mud-surface were coloured orange by the masses of living speci- 

 mens of the species, a phenomenon which has also been recorded 

 from the mud of the Dee Estuary by the late J. D. Siddall.^ 

 D'Orbigny goes on to point out that the animals are not tough, 

 ])ut decompose immediately after death, " which is brought about 

 by the least change in their habitual condition, and which makes 

 them very difficult to observe " (p. 246). This is not the case. 

 On the contrary, we have had occasion to remark how tenacious 

 of life these organisms really are. They can be kept for an 

 indefinite length of time in tanks of all sizes, and can be made to 

 flourish in artificial sea-water, and in sea-water modified in various 

 ways for purposes of experiment.- D'Orbigny observes further that 

 they are greedy eaters of Polyzoa,^ that they exist in myriads on all 



' J. D. SicMall, " Report on the Foraminifera of the Liverpool Marine Biology 

 Committee," Proc. Liverpool Lit. and Phil. Soc, xL, Appendix, p. 45. See also 

 "The Foraminifera of the River Dee," Ann. Mag. Nat. Hist., ser. 4, xvii. (1876) 

 p. 40. Schlumberger has dealt with this question of coloration of the proto- 

 plasm in the Feuille des Jeunes Naturalistes, 1882, No. 136, p. 42. 



" See the observations of Dujardin, j^ost, p. 40. 



^ See the letter of d'Orbigny pere, ante, p. 7. 



