42 PROCEEDINGS OF THE ACADEMY OF [Jan., 



Julus and Parajulus 165 158 



Polydesmus virginiensis ._.. 32 26 



Fontaria sp 2 2 



Lysiopetalum lactarium 16 6 



Spirobolus sp --— 1 1 



Lithohius forcipatus -— 13 4 



Scolopocryptops sexspinosus 6 3 



Scutigera forceps — 4 3 



Geophilus sp 8 



Elater sp 8 1 



Cucujid larva..- 5 2 



Disccelus ovalis — 2 2 



Harpalus caliginosus 1 ■ 1 



Dytiscus sp., larva 1 1 



It is headed with Julus and Parajulus. These two genera of Diplo- 

 pods are distinguished by characters of the mouth-parts and anterior 

 feet, but they are much alike and the smaller species of Parajulus are 

 but little larger than those of Julus. No attempt was made to distin- 

 guish between these two genera and much less between the various 

 species, but such an attempt w^ould have been of no especial utility, 

 even if successful. They are to be found together, beneath logs, stones 

 and leaves, and, as the list shows, they are almost invariably para- 

 sitized, the gregarine being Stenophora juli. It is possible to obtain 

 these Diplopods at any season of the year, and so far as my observa- 

 tions go, the gregarines have no seasonal cycle, but all stages are met 

 with at any time. Usually a given host contains a moderate number 

 of gregarines, from twenty to forty, these ranging from the largest 

 adults to the smallest intracellular stages. Frequently, however, 

 only a very few parasites are found in a host, and in such cases they 

 will be for the most part quite small. In none of the millipedes ex- 

 amined have I come across the cysts, nor, to my knowledge, the free 

 spores. 



In consideration of their gregarious habit, and their diet of rotten 

 wood and vegetable fibre, it is easy to see why Julus and Parajulus are 

 so persistently parasitized. It is also worthy of note that other animals 

 having the same mode of life and generally found in the same places do 

 not appear ever to contain gregarines. A case in point is that of the 

 Isoi^oda, Oniscus and Porcellio. These are almost always found with 

 Julus and Parajulus, and they doubtless frequently swallow the spores 

 of Stenophora. The isopod intestine is, however, lined with chitin, and 



