568 DR. CARPENTER'S RESEARCHES ON THE FORAMINIFERA. 



with an entire chamber of the earlier whorl, that the areolation of the outer wall may 

 be regarded as a sort of attempt at that complete subdivision of the cavity, which we 

 have seen to be fully carried out in Heterostegina (^f 114). 



231. Thus, then, it appears that not only in the minute structure of its shell, but also 

 in its general plan of conformation, Carpentaria essentially approximates to the ordinary 

 Foraminiferous type, its affinity to the Spongiada being rather apparent than real ; for 

 although each cone does at first view seem to resemble the papilla of a Sponge enclosed 

 in a shelly case with a terminal oscule, yet the internal structure of that cone does not 

 bear out that resemblance. The link of affinity, however, seems to be supplied by the 

 spongeous character of the animal substance which occupies the chambers (fig. 9) ; this 

 (according to the evidence aiforded by the dry specimens which alone I have had the 

 opportunity of examining) not only possessing far more consistence than the sarcode- 

 body of the Foraminifera, but being supported, in the large chambers at least (fig. 6), 

 by sponge-like spicules (fig. 16), whose form resembles that of the simplest spicules of 

 Halichondria, and whose composition is siliceous. 



232. The idea which had occurred to myself of the possibly parasitic nature of this 

 sponge-like substance, has been very strenuously advocated by Mr. BOWERBANK, on the 

 ground of the frequency with which the surface of dead coral and the valves of living 

 as well as dead shells are covered with Sponges, and the consequent probability that 

 any multilocular organism growing on such surfaces would be so penetrated by the 

 sponge that all its chambers would be filled by the parasite. The following consider- 

 ations, however, seem to me strongly to militate against such a view : 1st. That neither 

 on the surface nor in the substance of the specimen of Porites covered with the cones 

 of Carpenteria, nor on that of the valves of the Pecten and Cardita on which isolated 

 specimens of Carpenteria occur, is there the least trace of spongy structure : 2nd. That 

 notwithstanding this marked difference in their habitats, all the specimens of Carpenteria 

 yet examined have their cavities occupied by the same spongy substance : 3rd. That a 

 firm brownish yellow substance of far greater consistence than the sarcode of Forami- 

 nifera, is found to occupy even the smallest and earliest chambers of Carpenteria 

 (figs. 2, 4, a), filling them so completely that it can scarcely be supposed to be anything 

 but the animal body properly belonging to them ; and that although the substance in 

 question is there destitute of spicules (the chambers being too small to accommodate 

 them, as will be seen by the comparison of figs. 4 and 16, allowing for the difference 

 of magnifying power), yet it is obviously the same with that in which spicules are 

 copiously imbedded in the larger and later chambers : and 4th. That notwithstanding 

 the multitudes of sections of various Foraminiferous shells which 1 have made during 

 the la.st ten or twelve years, I have never found their chambers to be occupied by 

 a parasitic sponge of any description. I may add to these considerations the fact men- 

 tioned to me by Mr. DENIS MACDONALD, that he has met with various forms of branching 

 Sponges*, possessing a peculiarly solid calcareous skeleton, and in many respects 



* These specimens were collected during the voyage of H.M.S. ' Herald ' in the Australian Seas, and 



