68 ILLINOIS BIOLOGICAL MONOGRAPHS [68 



PILEOCEPHALUS HEERII (Kolliker) Schneider 

 [Figures 15, 16, 46, 72 and 73] 



Sporonts solitary, capable of great contractility due to unusually well- 

 developed myonemes. Trophozoite when quiescent long and arrow-shaped, 

 widest in middle and tapering in both directions, sharply acuminate at 

 extremities (Fig. 15). In sporonts the same general shape but much 

 contracted longitudinally and proportionally broader. (Fig. 16). Di- 

 mensions not given. Ratio LP:TL: : (quiet trophozoite without epimerite) 

 1:3 (contracted sporont 1:2). WP:WD: :1:1. Protomerite widest just 

 above septum, conical, apex truncate. Deep constriction at septum. 

 Deutomerite same shape, ending acuminately. Nucleus ellipsoidal 

 with many small karyosomes. ' Epimerite highly specialized. In young 

 trophozoites an elongate papilla sharply acuminate and situated upon a 

 short neck. In order specimens there devlops a spade-shaped or lanceolate 

 (in optical section) holdfast, at the end of a bulbous neck (the former 

 papilla). The neck and lance are of equal length and surmount the 

 truncate protomerite. The trophozoite in this form is a very beautiful 

 animal (Fig. 15). * 



Spores from cysts in feces biconical, which is the accepted form for the 

 type, as mentioned in the genus synopsis. 



A possible schizogony exists, for in this species cysts were encountered 

 in the coelom which developed triangular spores. Schneider attributes 

 these latter spores to the species in question but he suggests that they may 

 belong to another parasite. If the discovery is authentic, the fact adds 

 one link in the hypothesis of Minchin that the Cephaline Gregarines are 

 capable of schizogony as well as sporogony. If this should be proven an 

 impossibility, then the present species must be removed from the Eugre- 

 garinae and placed with the Schizogregarinae. 



Schneider found only triangular spores in the type species P. chinensis, 

 but does not state whether they emanated from coelomic or fecal cysts, 

 mentioning only the latter type of cysts. 



