On the Genus Orbitoides of d? Orhigny. 439 



possibly have been contained in the tissues lining the ccelora ; 

 but of this fact I cannot be absolutely certain. 



Summary, 



The most important facts recorded in this paper are the 

 follovvins; : — 



(1) Coccidium occurs in the Oligochset Perichmta. 



(2) In two species of Perichceta from different parts of the 



world (i. e. P. novcB-zelandice from New Zealand and 

 P. armata from Borneo) the same species, or at least 

 closely allied species, occur which differ from other 

 forms, 



(3) The cyst-membrane is double and the outer membrane 

 is of very great thickness, though extremely trans- 

 parent. 



(4) There is a conspicuous " micropyle " (often two) which 



does not appear to be a perforation of the cyst-mem- 

 brane, but merely a local bulging, perhaps due to 

 reagents. 



(5) The protoplasm of the parasite breaks up into a large 



number of spores. 



EXPLANATION OF PLATE XV. 



Lettering : — a, inner cyst-membrane ; b, outer cyst-membrane ; c, mi- 

 cropyle ; d, protoplasmic contents ; d', sporoblasts. 



Figs. 1-13, 15. Coccidium from Perichmta armata. 



Fig. 14. Gregarina, sp. ?, found in company with Coccidiuni in Perichceta 



armata. 

 Fig. 16. Coccidium from Perichceta novee-zealandice. 



LVIII. — On the Foraminiferal Genus Orbitoides of 

 d'Orhigny. By H. J. CARTER, F.R.S. &c. 



There are several discoid fossils among the Nummulites 

 which, having a central plane covered in on each side by a 

 more or less convex crust, look so much like Nummulites 

 that, without close inspection, they would appear to present 

 no difference; and these in totality have been named '"'Orhi- 

 toides " by d'Orbigny, whose diagnosis, together with typical 



