690 SCIENTIFIC KLCORD i'Oli 1884. 



depth of about 2,000 fathoms by the " Talismau," were subject to a criti 

 cal examination by C. Schlumberger. The appearance previously indi- 

 cated was observed anew ; "a succession of globuhir chambers, arranged 

 in a spiral fashion, like those of ceitain GlobUjerinrv,^' were found within 

 the shells of some of the small OrbaUnce, but not in all. In many, even 

 of the small ones, no manifestation whatever of such contents existed, 

 and " the ver}' large specimens also were nearly always empty."' Fur- 

 ther, on minute examination it was discovered that there w^ere essential 

 histological and structural differences between the globigerina-like 

 bodies of Orbulin(e aud true Globiyerincc. 



The ''plasmostracum" of the globigerina-like contents of the Orbu- 

 linoi is "extremely tine and traversed by widely scattered perforations ; " 

 the chambers forming the two tirst turns of the spiral are quite smooth, 

 while the following ones are provided with spines which reach as far as 

 the outer wall of the Orbidina and are there fixed firmly to it, and the 

 several chambers communicate with each other and also with the inte- 

 rior of the Orbidina. 



The plasmostracum or cell- walls of the true Globigerinw are relatively 

 thick, and punctured by closely approximated and numerous perfora- 

 tions. 



In fine, the resemblance between the contents of the Orbulincc and 

 true Globigerinw is simj^ly superficial, aud^ apparently, the most prob- 

 able explanation is that OrbuUna is another instance of dimorphism 

 among the Foraminifers such as has already been shown to exist in 

 other genera of that order by the author and Munier-Chalmas. ( Cotnptes 

 Henclus, xcviii, pp. 1002-1004; J. R. M. S. (2), iv, pp. 570-580.) 



Life history of a Relizoan Rliizopod. — The life history of a beautiful 

 Heliozoan, named Clathridina cicgans, has been studied by a lady of 

 Philadelphia, Miss Sara Gwendolen Foulke. This little rhizopod was 

 found 'mu myriads" attached to the roots of the Duck weed or Lemna. 

 In many cases they were seen in groups of "about twenty five colony- 

 stocks, so matted together by the twisting of the pedicels, and so sur- 

 rounded by waste matter, as com|)letely to conceal at that point the 

 supporting root fibre. The animals were in a most active condition, 

 feeding by means of their characteristic pseudopodial rays, and multi 

 plying so freely by self-division, that the water was full of the 

 Actinophrys-like bodies, and almost every capsule supported from one 

 to ten young individuals. Alter being kept in captivity for two weeks, 

 the large social groups had decreased in number, although solitary 

 individuals were much more numerous. Kei>roduction was still going 

 on, but not so freely, and by more varied methods. The i>henotnena 

 exhibited during the act of reproduction are the subject of this com- 

 municatiiui. 



'•The modes of reproduction are four in number, two of these being 

 sllgUtl) similtir, wliile the others essentially differ ia character. These 



