242 university of colorado studies 



Subclass HELIOZOA 



Typically freshwater' forms of actinate Protozoa in which there is no trace of a 

 chitinous central capsule separating ectoplasm and endoplasm (Calkins). (The 

 other subclass of Actinopoda is Radiolaria, exclusively marine.) 

 Our principal work of reference for the Heliozoa is Penard's Les Heliozoaires d' eau 

 douce (1904). 



Order APHROTHORACA 



Naked, except during encystment. 



Family ACTINOPHRYID^ 



A single nucleus. 



(56) Actinophrys Ehrenberg. The "sun-animalcule," so called from its spherical 

 form and long ray-like pseudopodia. A. sol Ehrenberg.* 



Order CHALAROTHORACA 



Covering made up of separate or loosely connected particles. 



Family HETEROPHRYID^ 

 With a thick protoplasmic or mucilaginous covering, in which are very fine spicules, 

 which extend outward in every direction as radiating filaments, much shorter 

 than the pseudopodia. Schaudinn and Calkins place this group in the order 

 Chalmydophora, which typically has a mucilaginous covering without solid ele- 

 ments. I follow Penard in placing it with the Chalarothoraca. 



(57) Heterophrys Archer. An undetermined species was found by Penard near 

 Caribou. The spicules in this genus are said to be chitinous, whereas those of the 

 Rhaphidophryidae {Rhaphido phrys and Rhaphidocystis) are. siliceous. 



Family ACANTHOCYSTID^ 



No true mucilaginous envelope; siliceous elements of two kinds, scale-like and 

 spine- or needle-like. The latter are often invisible in living specimens. 



(58) Acanthocystis Carter. Near Caribou Penard found a species which he recorded 

 doubtfully as A. myriospina Penard. A. myriospina has the plasma bluish, the 

 nucleus sublateral. It is 15 to 20 m in diameter, not counting the spinules, which 

 extend outward on all sides in the manner of Heterophrys. 



Order DESMOTHORACA R. Hertwig & Lesser 



Covering of one piece, perforated by numerous openings. 



Family CLATHRULINIDiE 

 Stalked forms. 



(59) Clathrulina Cienkowsky. The spherical shell with numerous round open- 

 ings; color yellowish or brown, darkening with age. C. elegans Cienk. This 

 beautiful species, originally described from St. Petersburg, Russia, was found near 

 Ward, Boulder County, in 1909, and studied by Dr. C. T. Burnett and the writer. 



' Penard enumerates eleven species which are marine. 



