690 SIJIENTIF.C m.CORD FOK 1884. 



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

 cal examination by 0. Schlumberger. The appearance previously indi- 

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

 in a spiral fashion, like those of certain Globigerinw,''^ were found within 

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

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

 and " the very large specimens also were nearly always emiity.'' Fur- 

 ther, on Djinute examination it was discovered that there were essential 

 histological and structural differences between the globigerina-like 

 bodies of OrhuUna; and true GlohUjcrincv. 



The ''plasmostracnm" of the globigerina-like contents of the Orhti- 

 lincc is "extremely fine and traversed by widely scattered perforations ;" 

 the chambers forming the two first 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 Orbttlina and are there fixed firmly to it, and the 

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

 rior of the OrhuUna. 



The i)lasmosti'acum or cell walls of the true Glohigerincc are relatively 

 thick, and punctured by closely approximated and numerous perfora- 

 tions. 



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

 true Glohigerince is simply superficial, and, apparently, the most prob- 

 able explanation is that Orbulina is another instance of dimor|)hism 

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

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

 Mendns, xcviii, pp. 1002-1004; J. R. M. 8. (2), iv, pp.57D-580.) 



Life history of a Helizoan Rhizopod. — The life history of a beautiful 

 Heliozoan, named ClathruUna eJegans, has been studied by a lady of 

 Philadelphia, Miss Sara Gwendolen Foulke. This little rhizopod was 

 found "in 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 completely 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. After being kept in captivity for two weeks, 

 the large social groups had decreased in number, although solitary 

 individuals were much more numerous. Reproduction was still going 

 on, but not so freely, and by more varied methods. The phenomena 

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

 munication. 



"The modes of reiiroduction are four in number, two of these being 

 slightly similar, while the otiiers essentially differ in character. These 



