HELIOZOA RADIOLARIA 



77 



. Spumellaria. 



Sublegion (1). CoLLODARiA.1— Skeleton absent or of detached spicules; 

 colonial or simple. 

 Order i. Coixoidea.- Skeleton absent. (Families 1, 2.) Thcdassicolla 

 Huxl.; nalassophysa Haeck. ; Collozoum Haeck. ; Gollosphaera 

 J. Mull. ; Achssa Haeck. 

 Order ii. Beloidea.— Skeleton spicular. (Families 3 4) 

 Sublegion (2). SpHAERELLARiA.-Skeleton continuous, latticed or spongy. 



r6tlCl.lJ.9it6. 



Fig. 23.— Aciinomma asiemcanthion. A, the shell with portions of the two outer 

 spheres broken away ; B, section showing the relations of the sheleton to the 

 animal, cent, caps, Central capsule ; ex. caps.pr, extra-capsular protoplasm ; nu, 

 nucleus ; sk. 1, outer, sk. 2, middle, sk. 3, inner sphere of skeleton. (From Parker 

 and Haswell, after Haeckel and Hertwig.) 



Order iii. Sphaeroidea. — Skeleton of one or several concentric 

 spherical shells; sometimes colonial (Families 5-10.) Haliomma 

 Ehrb. ; Aciinomma Haeck. (Fig. 23). 



Order iv. Prdnoidea. — Skeleton a prolate sphaeroid or cylinder, 

 sometimes constricted towards the middle, single or concentric. 

 (Families 11-17.) 



Order v. Discoidea. — Shell flattened, of circular plan, simple or con- 

 centric, rarely spiral. (Families 18-23.) 



Order vi. Larcoidea. — Shell ellipsoidal, with all three axes unequal 

 or irregular, sometimes becoming spiral. (Families 24-32.)^ 



^ K. Brandt, in Arc.'i. Prot. i. 1902, p. 59, regards the presence of spicules as not 

 even of generic moment, and subdivides the Collodaria into two families — Collida 

 (solitai'y), and Sphaerozoea, colonial, i.e. with numerous central capsules. 



^ Dreyer adds an additional order — Sphaeropylida, distinguished by a basal (or 

 a basal and an apical) pylome. 



