CHYTRIDIALES 181 



*R.OZELLA MAXIMUM 



A species name used by Karling (1942a: 24) in error, presumably 

 for Rozella marina Sparrow. 



IMPERFECTLY KNOWN GENERA OF THE OLPIDIACEAE 



? BLASTULIDIUM Perez 

 C. R. Soc. Biol., 55: 715, figs. A-E. 1903 



? BLASTULIDIUM PAEDOPHTHORUM Perez 



Loc. cit. 



Thallus endobiotic, with a thin wall, ellipsoidal, 25 \i long by 20 \i 

 in diameter, or consisting of a few cells with short rudimentary branch- 

 es; sporangium inoperculate, formed from the whole thallus or its 

 segments; zoospores ovoid, with one long axillary flagellum, formed 

 in the sporangium, where motion is initiated, and escaping from it 

 through a short neck; resting spore (?) citriform, with a thickened 

 wall, germination not observed. 



Parasitic in eggs and embryos of various Crustacea, Daphnia obtusa, 

 Simocephalus vetulus, Chydorus sphaericus, Lynceus, larvae of Corethra 

 (gnat), Perez {loc. cit.), Chatton (1908: 34), France. 



Perez considered the organism a haplosporidian (Protozoa), but Chat- 

 ton, after noting the flagellation of the spore, referred it to the chytrids, 

 particularly to Olpidium and Synchytrium. 



The genus is a puzzling one, and, since no clear picture of it is given 

 by either Perez or Chatton and the term "axillary ,, does not indicate 

 to what pole of the spore the flagellum is attached, it will remain so 

 until new observations of a purely morphological nature are made. 

 It may be related to Septolpidiam. 



Blastulidium was considered distinct from Olpidium by Chatton be- 

 cause of the formation of a large central vacuole and the fact that 

 the thallus was occasionally septate and yeastlike. 



Perez described external ellipsoidal bodies adherent to the Crustacea 

 as possibly representing the resting styge, but Chatton believed these 

 to be single or conjugated zoospores which had fixed themselves on 

 the animal, infected it, and developed. The resting stage observed by 



