140 ILLINOIS BIOLOGICAL MONOGRAPHS [350 



of equal density in protomerite and deutomerite. Nucleus large, spheri- 

 cal, containing several karyosomes. 



Cysts spherical, 640/* in diameter, dehiscing by simple rupture. 

 Spores 9 by 7.5/1,, diamond shaped. 



Taken at Wyncote, Pa. Host: Harpalus caliginosus Fab. Habi- 

 tat : Intestine. 



"These gregarines were present in the intestine of the one beetle examined 

 in hundreds." 



ACTINOCEPHALUS DICAELI (Crawley) Watson 

 [Figure 100] 



1903 Gregarina discaeli Crawley 1903 :47 



1903 Gregarina dicaeli Crawley 1903a :641 



1913 Actinocephalus discaeli Ellis 1913b :279 



1916 Actinocephalus dicaeli Watson (This paper) 



Actinocephalus: Sporonts solitary, greatly elongate. -Length 

 1200/t. Ratio length protomerite : total length : : 1 : 15 ; width pro- 

 tomerite : width deutomerite : : 1 : 1.2. Protomerite pentagonal, seen 

 in lateral optical section, widest through middle, flattened on top, width 

 about equal to height. Slight constriction at septum. Deutomerite 

 very elongate, cylindrical, slightly tapering to a blunt point. Epimerite 

 not known. Endocyte dense, opaque in deutomerite, nearly transparent 

 in protomerite. Nucleus spherical, with several karyosomes. Cyst and 

 spores not known. 



Taken in Pennsylvania. Host : Dicaelus ovalis Lee. Habitat : Intes- 

 tine. 



Crawley placed this species in the genus Gregarina, with a question. 

 In his later paper (1903a) he left it in the same genus but in a list of 

 eight doubtful species. 



"This gregarine is placed in the genus Actinocephalus because of the general 

 shape of the sporont and the coleopteran host; it was removed from the genus 

 Gregarina because the sporonts do not form associations." 



Its generic position is still doubtful and from the data at hand 

 might belong to any of these families: Actinocephalidae, Stylocephali- 

 dae or Acanthocephalidae. 



The generic name of the host and the specific name of the parasite 

 were both misspelled by Crawley in his original paper. This error was 

 corrected in his second memoir ; but Ellis copied the original error, over- 

 looking Crawley 's careful explanation of the misprint. 



