88 ILLINOIS BIOLOGICAL MONOGRAPHS [298 



Crawley referred the gregarine which was described by Leidy as 

 G. megacephala (Fig. 35) to the present species because of the elongate 

 appendage on the protomerite. That this position is correct is attested 

 by the fact that Crawley himself found the species, the specimens agree- 

 ing with Schneider's figures and with the dimensions as given by Leidy. 

 Crawley 's description is as follows : 



"This form is well described by A. Schneider whose figure also is excellent, 

 giving a very accurate idea of the actual animal. Schneider, however, gives no 

 dimensions, while Leidy says that the dimensions vary from 420 to 750 microns, 

 these figures agreeing very closely with those which I obtained. 



"My own observations on this species show it to be an active, very poly- 

 morphic gregarine, with the ability to undergo extensive alterations in shape. Thus, 

 the anterior end of the protomerite, normally a blunt curve, frequently protrudes 

 in a long tongue-shaped process. The peristaltic movement so frequently dis- 

 placed by gregarines, may, in this species, pass forward as well as backward. This 

 indicates that here the contractile elements are capable of operating as well in one 

 direction as another, which is certainly not the case in most polycystid gregarines. 

 Fusion, preparatory to encystment, was seen to take place 'head to head.' " 

 Leidy 's brief account of the species is as follows: 



"One morning I found a fine Cermatia forceps in my bedroom. It was 



species which may be named Gregarina megacephala. The body is elongated 



ovate and acute or short clavate and obtuse with an unusually large ovoid and 

 often constricted head, surmounted by a small rounded or elongated appendage. 

 Length 0.42 to 0.75 mm. by 0.24 broad ; head about one-fourth the length of the 

 body. It approximates Dufouria agilis of Schneider, found in the larvae of a Hy- 

 dracantharis." 



The latter species lacks the elongated proboscis; it is now known 

 as Legeria agilis (Schn.) Labbe. For description and drawing, see 

 chapter on Coleoptera. 



RHOPALONIA GEOPHILI Leger 



1894 Rhopalonia geophili 

 1896 Rhopalonia geophili 



Rhopalonia: Sporonts solitary, dicystid, obese. "Widest at ante- 

 rior end, tapering to a point. Length 500/x. Epimerite a large hyaline 

 subspherical plate with a corona of ten to fifteen backwardly directed 

 digitiform processes placed above the protomerite on a short neck. 

 Endocyte with large yellow-orange granules. Nucleus ovoidal, contain- 

 ing several karyosomes. Cysts spherical, 200 to 250/t, the fertile half 

 brown, the sterile half white, a black equatorial band marking the future 



