PROTOZOA 



21 



Fam. 3. THALASSICOLLIDA. Peripylsea devoid of a skeleton, or 

 with a skeleton composed of loose siliceous spicules only. Nucleus 

 single ; central capsule and general protoplasm spherical. 



Genera (selected). Thalassicolla, Huxley (Fig. XIII., Fig. 

 XIV. 1) ; Thalassosph&ra, Haeck. ; Physematium, Haeck. 



Fam. 4. POLYCYTTARIA. Peripylaea consisting of colonies of 

 many central capsules united by their extracapsular protoplasm. 

 Central capsules multiplying by fission. Nuclei in each central 

 capsule numerous. Siliceous skeleton either absent, or of loose 

 spicules, or having the form of a spherical fenestrated shell sur- 

 rounding each central capsule. 



Genera (selected). Collosphsera, Miiller (with fenestrated globular 

 skeleton) ; Sphserozoum, Haeck. (skeleton of numerous loose spicules 

 which are branched) ; Saphidolioum, Haeck. (spicules simple) ; Col- 

 lozoum, Miiller (devoid of skeleton, Fig. XIV. 2, 3, 4, 5). 



Fro. XIV. Radiolaria. 1. Central capsule of Thalassicolla nucleata, 

 Huxley, in radial section, a, the large nucleus (Binnenblaschen); b, 

 corpuscular structures of the intracapsular protoplasm containing con- 

 cretions ; c, wall of the capsule (membranous shell), showing the fine 

 radial pore-canals ; d, nucleolar fibres (chromatin substance) of the 

 nucleus. 2, 3. Collozoum inerme, J. Miiller, two different forms of 



colonies, of the natural size. 4. Central capsule from a colony of 



Collozoum inerme, showing the intracapsular protoplasm and nucleus, 

 broken up into a number of spores, the germs of swarm-spores or flagelluls? ; 



each encloses a crystalline rod. c, yellow cells lying in the extracapsular 

 protoplasm. 5. A small colony of Collozoum inerme, magnified 25 



diameters, a, alveoli (vacuoles) of the extracapsular protoplasm ; b, 

 central capsules, each containing besides protoplasm a large oil-globule. 

 6-13. Yellow cells of various Eadiolaria : 6, normal yellow cell; 7, 8. 

 division with formation of transverse septum ; 9, a modified condition 

 according to Brandt ; 10, division of a yellow cell into four ; 11, amceboid 

 condition of a yellow cell from the body of a dead Sphserozoon ; 12, a 

 similar cell in process of division ; 13, a yellow cell the protoplasm of 

 which is creeping out of its cellulose envelope. 14. Heliosphxra 



inerinis, Haeck., living example; x 400. a, nucleus; b, central capsule ; 

 c, siliceous basket-work skeleton. 15. Two swarm-spores (tta^ellula?) 



of Collozoum inerme, set free from such a central capsule as that drawn in 

 4 ; each contains a crystal 6 and a nucleus a. 16. Two swarm-spores 



of Collozoum inerme, of the second kind, viz., devoid of crystals, and of 

 two sizes, a macrospore and a microspore. They have been set free 

 from central capsules with contents of a different appearance from that 

 drawn in 4. a, nucleus. 17. Actinomma asteraeanthion, Haeck ; x .260; 

 one of the Peripytea. Entire animal in optical section, a, nucleus; 

 b, wall of the central capsule ; c, innermost siliceous shell enclosed in the 

 nucleus ; c 1 , middle shell lying within the central capsule ; c 2 , outer shell 

 lying in the extracapsular protoplasm. Four radial siliceous spines, hold- 

 ing the three spherical shells together are seen. The radial fibrillation of 

 the protoplasm and the fine extracapsular pseudopodia are to be noted 

 18. A i/iphilonche messanensii, Haeck; x 200; one of the Acanthometridea. 

 Entire animal as seen living. 



ORDER 2. MOXOPYL^A, Hertwig. 



Characters. Silico-skeletal Radiolaria in which the central cap- 

 sule is not spherical but monaxonic (cone-shaped), with a single per- 

 forate area (pore-plate) placed on the basal face of the cone ; the 

 membrane of the capsule is simple, the nucleus single ; the skeleton 

 is extracapsular, and forms a scaffold-like or bee-hive-like structure 

 of monaxonic form. 



Flfl. X.V.Eucyrtidium cranioides, Haeck ; x!50 ; one of the Monopykea. 

 Entire animal as seen in the living condition. The central capsule is 

 hidden by the bee-hive-shaped siliceous shell within which it is lodged. 



Fam. 1. PLECTIDA, Haeck. Skeleton formed of siliceous spines 

 loosely conjoined. 



Genera (selected). PTagiacantha, Haeck. ; Plegmatium, Haeck. 



Fam. 2. CTRTIDA, Haeck. Skeleton a monaxonic or triradiate 

 shell, or continuous piece (bee-hive-shaped). 



Genera (selected). Halicalyptra, Haeck. ; Eucyrtidium, Haeck. 

 (Fig. XV.); Carpocanium, Haeck. (Fig. XVI. 3). 



Fam. 3. BOTRIDA, Haeck. Irregular forms ; the shell composed 

 of several chambers agglomerated without definite order ; a single 

 central capsule. 



Genera. Botryocyrtis, Haeck. ; Lithdbotrys, Haeck. 



Fam. 4. SPYRIDA, Haeck. Gemminate forms, with shell con- 

 sisting of two conjoined chambers ; a single central capsule. 



Fam. 5. STEPHIDA, Haeck. Skeleton cricoid, forming a single 

 siliceous ring or several conjoined rings. 



Genera (selected). Acanthodesmia, Haeck. ; Zygostephanus, 

 Haeck. ; Lithocircus, Haeck. (Fig. XVI. 1). 



ORDERS. PH.EODARIA, Haeck. (Tripyltea, Hertwig). 

 Characters. Silico-skeletal Radiolaria in which the central 



