5^0 WILLIAM BLAXLAND BENHAM. 



will^ I hope, enable this form to be discovered in England 

 and similar observations on the habits of other forms are a 

 great desideratum. 



Parasites of Criodrilus. — My attention was first at- 

 tracted to certain curious elongated structures attached to the 

 ovary, and I found them afterwards in various parts of the 

 body. These are narrow bodies, about one tenth of an inch in 

 length, and of a white colour (in spirit). Each is invested by 

 a well-defined cuticle, which encloses a very granular dark 

 medullary protoplasm, in which is a clearer space, probably 

 the nucleus. The shape varies to a great extent ; some consist 

 of an elongated ovoid body drawn out at each end into a much 

 narrower portion; others are just the reverse, consisting of two 

 ovoid swellings connected by a narrower portion. 



They are apparently Gregarinse, which have been killed in 

 various states of englenoid movement, such as is exhibited by 

 Monocystis lumbrici; the worms had been killed in cor- 

 rosive sublimate, judging from the white deposit on their 

 surface, and this would cause the various states of movement 

 to be fixed. At one end the cuticle is thickened and presents 

 somewhat the appearance figured by Professor Lankester in 

 vol. 3 of this Journal, PI. VII, for M. aphroditse. 



EXPLANATION OF PLATE XXXVIII, 



Illustrating Dr. Orley's Paper ''Observations on Criodrilus 

 lacuum," figs. 1 to 8, and Mr. Benham's Paper '' Studies 

 on Earthworms,^^ figs. 9 to 19. 



Criodrilus lacuum, Hoffmeister. 



Fig. 1.— Cocoon of Criodrilus lacuum. Natural size. «. The end by 

 \?bich it is attached, b. The free end. 



Tig. 2. — The attachable end more highly magnified. ( x 300.) 



