EEPORT ON THE RADIOLARIA. 35 



differs from the latter by the possession of spicula in the calymma. The peculiar 

 " ceutripetale Zell-gruppeu " on the inside of the capsule-membrane are probably due to 

 radial cleavages of the endoplasm ; as also occurs in other Collodaria. 



1. Physematium mulleri, Schneider. 



PJiTjsematium mulleri, Schneider, 1858, Archiv. f. Anat. u. Physiol., p. 38, Taf. iii. B, 



figs. 1-5. 

 Physematium miilleri, Haeckel, 1862, Monogr. d. Eadiol., p. 256, Taf. iii. figs. 6-9. 



Spherical body limpid, somewhat opalescent, sometimes a little yellowish or brownish, rather 

 soft. Central capsule witli a thin, but firm, transparent membrane, its diameter eight to ten 

 times as large as that of the central spherical nucleus. Membrane of the nucleus thick, porous, 

 on its inside with some nucleoli. In the protoplasmic network between the large intracapsular 

 alveoles, numerous large, pale, yellowish, or orange oil-globules. On the inside of the membrane 

 numerous conical bodies, centripetally directed with the apex towards the centre ; every conical bodj' 

 (" kegelformige ceutripetale Zellgruppe ") composed of three to nine (commonly four or five) nucleated 

 cells (mother-cells of the spores ?) ; in the axis of the cone there is often a yellowish, orange, or 

 brown oil-globule. Extracapsular jelly-envelope thin, with short pseudopodia. Xanthellse scarce 

 or wanting. Spicula scattered in the jelly numerous, small, simple needles, commonly C- or S-like 

 curved, smooth. 



Dimensions. — Diameter of the whole jelly-sphere 3 to 6 mm., of the central capsule 1 to 5 m:n., 

 of the nucleus 01 to 0-5, length of the spicula 0'05 to O'l. 



Habitat. — Mediterranean, Messina ; Schneider, Haeckel ; surface. 



2. Physematium atlanticum, Meyen. 



Physematium atlaniieum, Meyen, 1834, Nova Acta Acad. Nat. Curios., vol. xvi., Suppl., 

 p. 286 (162), Taf. xxxviii. (xxviii) figs. 1-3. 



Spherical body opalescent, jsearl-like, with a violet or purple lustre, very soft. Central 

 capsule with a strong, semi-transparent membrane, its diameter six to eight times as large as that of 

 the central spherical nucleus. Membrane of the nucleus very thick, porous, on its inside with 

 many small nucleoli. In the protoplasmic network between the alveoles very numerous, small, purple 

 oil-globules. On the inside of the membrane a continuous simple layer of small niiclei, enclosed in 

 radially striped protoplasm (mother-cells of the spores ?). No centripetal conical bodies. Extra- 

 capsular jelly-envelope very tliin, with short pseudopodia. No xanthellffi. Spicula scattered in the 

 jelly numerous, smaU needles, straight or slightly curved, thorny owing to numerous small vertical 

 spinules. This species and Thalassolam-pe maxima (p. 17) possess the largest central capsule. 



Dimensions. — Diameter of the whole jelly-sphere 8 to 12 mm., of the central capsule 5 to 

 10 mm., of the nucleus 1 to 2 mm., length of the spicula O'l to 0-3. 



Hahitat. — Eastern Atlantic, between Canary Islands and Cape Verde Islands, Meyen • 

 Lanzerote, Haeckel. 



