509 



Now in Tinoporus baculatus we often find columns of solid shell- 

 substance interposed between the angular partitions of the piles of 

 superposed cells, just as they are in Orbitoides, their summits being 

 visible on the surface as projecting tubercles ; these columns are 

 perforated with pseudopodian canals, which are extensions of the pores 

 in the walls of the chambers over which they lie. And the peculiar 

 stellate projections which give to this species so much the aspect of 

 a Calcarina are for the most part formed of a similar growth ; for 

 though the chambered structure is continued for a short distance as a 

 conical protuberance into the base of each, yet this cone is invested 

 and extended by a sheath of solid shell-substance, which is perforated 

 by pseudopodian tubes extending through it from the chambers. 



The last type of Foraininiferous structure described in this com- 

 munication is one which appears to furnish a highly interesting link 

 of connexion between Foraminifera and Sponges. Its nature was at 

 first entirely misunderstood ; the specimens in Mr. Cuming's collec- 

 tion having been supposed, not only by Mr. Cuming, but by other con- 

 chologists, to be shells of a sessile Cirripede. Their external resem- 

 blance might readily justify such an inference ; since they are irre- 

 gular cones, apparently composed of distinct valves, attached by a 

 spreading base to the surface of shells or corals, and having a single 

 orifice at their apex. A careful examination of the interior structure, 

 however, makes it evident that the shell is multilocular, and that it 

 is formed upon the type of the Helicostegue Foraminifera, closely 

 resembling Globigerina in the commencement of its growth ; the 

 supposed ' valves ' being the walls of the outer whorl, the chambers 

 of which are very large, and are partially subdivided by incomplete 

 septa. All the principal chambers communicate by orifices of their 

 own with a sort of central funnel which leads to the external orifice ; 

 and thus their relation to it is very much that of the separate orifices 

 of the chambers of Globigerina to its umbilicus. The cavities of the 

 chambers are occupied by a spongeous tissue, which contains sili- 

 ceous spicules ; and although the possibility that this spongy sub- 

 stance may be parasitic must not be lost sight of, yet reasons are 

 given which seem to render it almost certain that this is the proper 

 body of the organism, on which Dr. Gray, who first discerned its 

 true affinities, has conferred the generic name of Carpenteria. 

 The author concludes with some general observations upon the 



