NATURE OF MOBIUSISPONGIA PAEASITICA. 319 



cruise. The fossil forms have been apparently confused in some 

 cases with the Dentalina aculeata of D'Orhignj, and need careful 

 revision. 



Eecent forms have been so far included in R. glohulifera, 

 Brady, which measure about a fifteenth of an inch (1*7 millim.) 

 or more in leugth. 



The specimen found in the chamber of Carpenteria differs 

 therefore from the type in its smaller size as well as in the more 

 sinuous and irregular shape of the chambers, but the difference 

 seems scarcely sufficient to justify a separate specific name. 



Very probably the organism was " Polymorphine " in its early 

 stages like the Hamulina Gnmaldli described by M. Schlura- 

 berger * as growing among other organisms on dead shells. 

 Future research will doubtless reveal the existence of several 

 species of such adherent types, and the chambers and tubes to 

 which the name Hamulina was first given may be only their 

 detached fragments. 



In this case the animal in its young stage was probably sur- 

 rounded by the rapidly growing Carpenteria, but managed to 

 live for some time by means of the water circulating through the 

 chamber of the larger Foraminifer, That its growth under such 

 circumstances would be limited is very natural, and its charac- 

 teristics may be regarded as due to abnormal conditions rather 

 than to specific distinctness. 



It is not likely that the Hamulina grew in the chamber of tlie 

 Carpenteria after the death of the latter, as the chambers are 

 still lined with dry sarcode while those of the Hamulina are empty. 

 It is also difficult to suppose that a Hamulina could perforate 

 the dead walls of a Carpenteria and extend its stolon-tubes into 

 adjacent cavities. 



On the other hand, if both organisms were living at the same 

 time, either the Hamulina must have obtained food by taking it 

 direct from the Carpenteria^ or more probably the protoplasm of 

 the latter in the living state only lines the chambers, leaving a 

 clear space in the centre through which water can circulate. 



* Mem. Soc. Zool. France, iv. (1891), p. 509. My thanks are due to 

 M. Schlumberger for a copy of the plate illustrating his description. 



26* 



