REPORT ON THE RADIOLARIA. 1531 



larger forms it is often filled by numerous large alveoles, which are usually absent in 

 the smaller forms. These extracapsular alveoles are most strongly developed in the 

 calymma of the Phseocystina, or the PH/EODARIA with incomplete skeleton, 

 embracing the three families Phseodinida, Cannorrhaphida and Aulacanthida (Pis. 101- 

 104). Usually the calymma is here very voluminous and entirely filled up by large 

 alveoles, which are either spherical, irregularly roundish, or polyhedral by mutual 

 compression. These alveoles or vacuoles have no peculiar wall, but are only cavities in 

 the homogeneous substance of the jelly, and are filled by a clear aqueous fluid. 

 Between these the network of the anastomosing pseudopodia is expanded. They exhibit, 

 therefore, the same shape, as was first observed in Thalassicolla and in the Poly- 

 cyttaria (Collozoida, Sphserozoida and Collosphserida). 



The relation of the calymma to the skeleton is in the PH^ODARIA of the same 

 importance as in the other Eadiolaria, and we may also here distinguish a primary and 

 a secondary calymma. The primary calymma is that on the surface of which at a 

 certain period of life (in the " shell-building period ") the fenestrated shell is secreted in 

 the majority of PH^EODARIA. The secondary calymma, however, is formed after this 

 period, and envelops the shell itself as well as its apophyses externally. Usually the 

 entire skeleton seems to be enveloped by the secondary calymma. 



The parts of the extracapsular body, which are enclosed in the gelatinous calymma, 

 possess a peculiar importance in the PH^EODARIA ; these are firstly the sarcomatrix and 

 the pseudopodia arising from it, and secondly the phseodium. The sarcomatrix, or 

 the layer of extracapsular sarcode (ectoplasm), which immediately surrounds the central 

 capsule, is very thick and more strongly developed in all PHJEODARIA than in all other 

 Radiolaria. Its extraordinary size has been already mentioned by Hertwig (1879, loc. 

 cit., p. 99). It is in direct connection with the intracapsular sarcode (or the endoplasm) 

 only by the openings of the central capsule, and mainly by the astropyle. Very 

 numerous radial pseudopodia arise everywhere from the sarcomatrix and run to the 

 surface of the calymma, usually forming a rich network in it by means of numerous 

 branches and anastomoses (compare PI. 101-104). On the surface of the calymma 

 the meshes of this network are very numerous, and there arise from its nodal points 

 the terminal pseudopodia, which float freely in the surrounding water. The metamor- 

 phoses of this network of sarcode, the perpetual changes in the number and size of its 

 meshes, and the movements of the sarcode streams as well as of the small granules 

 running in it, are always very manifest in the PHJEODARIA and in the big forms of 

 this legion (mainly in the Aulacanthida) they are better observed than in the majority 

 of other Radiolaria. In many PH^EODARIA (and perhaps in all) a part of the pseudo- 

 podia seems to have undergone a local differentiation, for special physiological pur- 

 poses ; and Hertwig has described a peculiar conical contractile body, which arises in 

 Ccelodendrum between the two parapylse (loc. cit., p. 100, fig. 3). Further examination 



