28 CALIFORNIA ACADEMY OF SCIENCES. 



H. Stepanoivi from the blood of Emys, the fresh- 

 water turtle of Europe, and it may be considered fairly 

 certain that all forms related to Hgemagregarina are 

 true blood parasites, principally inhabiting the blood- 

 corpuscles of the vertebrates, turtles, birds and lizards 

 while adult. The spores again are found in the bone 

 marrow of the turtle, the kidneys, spleen and bone mar- 

 row of the lizard. This habitat of all the species of this 

 group makes the presence of a H^magregarina in the 

 blood of an oligocheet all the more interesting. The want 

 of large blood corpuscles in the blood of oligoch^ta has 

 made it necessar}^ for our present species to select an- 

 other habitat, if indeed it is not the original one. Here 

 it is the lining of the blood-vessels and the surrounding 

 mesenterial tissues which are infested, especially so the 

 lining of the blood lacunes in the alimentary canal; in no 

 instance did I find any of these protozoas in the blood it- 

 self. 



The youngest form was straight, slightly sigmoid, with 

 no well defined nucleus, while the more advanced indi- 

 viduals were folded together like the blade and handle of 

 a pocket-knife, as far as I can judge from drawings very 

 similar to HcBinagr egarina Stefanowi. The anterior end, 

 however, differs from that of this species by having a 

 slight prolongation, which in fully developed individuals 

 was shai^ply pointed, but in less developed ones only ap- 

 pearing as a serrated surface of the thicker apex. The 

 most advanced specimens possessed a circular nucleus 

 near the thicker apex, while less advanced individuals 

 showed an oblong, less well-defined nucleus nearer the 

 middle of the body bend. Each individual was sur- 

 rounded by a dry, thin cyst, considerably distant from its 

 body, causing it to lie in a large pellucid vacuol. 



