EEPORT ON THE RADIOLARIA. Ixvii 



surface of the central capsule ; at the apical portion of the latter the sarcomatrix is 

 often so thin that it can only be recognised by the aid of reagents ; it separates the 

 membrane of the central capsule from the surrounding calymma. The pseudopodia, 

 which penetrate the latter and by loose anastomoses form a wide-meshed sarcoplegma 

 within it, are usually not very numerous. The greater j)art of them radiate in a launch 

 downwards from the basal disc of the sarcomatrix, and a smaller number arise from 

 the thinner envelope which covers the remainder of the central capsule (PI. 51, fig. 13; 

 PL Q5, fig. 1; PI. 81, fig. 16). On the outer surface of the calymma the collopodia, 

 which have passed through it, unite to form the sarcodictyum, and through the 

 silicification of this the primary lattice-shell arises in the great majority of the 

 Nassellaria. From the surface of the sarcodictynm arise the astropodia, or free 

 pseudopodia which radiate outwards into the water. Their number in most Monopylea 

 is relatively small, but their- length appears to be very great. 



100. TJie Exoplasm of the Cannopylea. — The extracapsular protoplasm of the 

 Ph^odaria or Cannopylea is much better developed as regards volume than in the 

 other three legions, and is connected with the intracapsular sarcode by only a few 

 apertures in the capsule-membrane. In most Ph^odaria three of these are present, 

 the astropyle or main-opening at the oral pole of the main axis, and the two lateral 

 parapylse or accessory openings on either side of the aboral pole (§ GO). In several 

 families the latter appear to be wanting, whilst in others their number is increased ; 

 these families have not yet, however, been observed during life. The protoplasm 

 projects both from the oral main-opening and from the two aboral accessory openings 

 in the form of a thick cylindrical rod ; the tube into which each opening is produced 

 in many Phjeodaria (longer in the case of the astropyle, shorter in the parapylse) 

 being regarded as an excretion from this protoplasmic cylinder. The sarcode threads 

 within the tube appear like a bundle of fibrils, either quite hyaline or finely striated- 

 After issuing from the mouth of the aperture they pass over into a thick sarcomatrix, 

 which surrounds the central capsule entirely and separates it from the enclosing 

 calymma. In the neighbourhood of the basal astropyle the sarcomatrix is usually 

 swoUen into a thick lenticular disc, which is in dii-ect contact with the peculiar 

 phgeodium of this legion (§ 89). The pseudopodia, which radiate from the sarcomatrix, 

 and form by anastomosis a wide-meshed sarcoplegma within the calymma, are usually 

 not very numerous in the Ph^odaria, but are very strong. Sometimes two stronger 

 bundles of collopodia may be distinguished at the two poles of the main axis, an oral 

 bundle (in the direction of the proboscis of the astropyle) and an aboral bundle (at the 

 opposite pole between the parapylse). The collopodia of the sarcoplegma unite at the 

 surface of the calymma into a regular or irregular sarcodictyum, which, in most 

 Ph^odaria produces by the secretion of a peculiar silicate the primary lattice -shell. 



