HELIOZOA RADTOLARTA 



77 



A. Spumellaria. 



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

 colonial or simple. 

 Order i. Colloide a. Skeleton absent. (Families 1, 2.) Thalassicolla 

 Huxl. ; Thalassophysa Haeck. ; Collozoum Haeck. ; Collosphaera 

 J. Mull. ; Actissa Haeck. 

 Order ii. Beloide a. Skeleton spicular. (Families 3, 4.) 

 Sublegion (2). Sphaerellaria. Skeleton continuous, latticed or spongy, 

 reticulate. 



cent, caps 



7ZU 



Fig. 23. Actinomma asteracanthion. A, the shell with portions of the two outer 

 spheres broken away ; B, section showing the relations of the skeleton 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. ; Actinomma Haeck. (Fig. 23). 



Order iv. Prunoidea. 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.) 2 



1 K. Brandt, in Arch,. Prot. i. 1902, p. 59, regards the presence of spicules as not 

 even of generic moment, and subdivides the Collodaria into two families Co llida 

 (solitary), and Sphaerozoea, colonial, i.e. with numerous central capsules. 



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

 a basal and an apical) pylome. 



