GENUS HYALOSPHENIA— HYALOSPHENIA PAPILIO. 131 



individuals was found again, and presented the appearance seen in fig. 10, 

 with the sarcode contracted into the fundus of the shell. 



From first to last a nucleus appeared to be absent in the sarcode. The 

 endosarc contained fine granular matter, coarser, darkly defined granules, 

 oil-like globules, clear vacuoles, and a few brown food particles. 



Hyalosplienia cuneata, with this name, was first described by Stein. 

 What appears to be the same was afterward described by Tatem, in Eng- 

 land, under the name of Difflugia ligata. Schulze subsequently described 

 what he regards as a distinct species from that of Stein under the name of 

 Hyalosplienia lata I have not access to the description of the latter author; 

 but from its quotation by Schulze I cannot detect sufficient difference to 

 distinguish two species. 



Stein remarks that in H. cuneata the animal can abruptly and quickly 

 separate from the mouth of the shell and retract to the bottom. Schulze 

 remarks that in H. lata he never observed such a sudden contraction as 

 this. That this apparent difference of habit has no specific value is shown 

 in the fact, that most lobose rhizopods, when disturbed, may retract their 

 pseudopods, but retain the connection of the sarcode mass with the mouth 

 of the shell, notwithstanding the rudest shaking, while at other times any 

 of them may and will sever the connection and quickly retreat to the 

 fundus of the shell. 



The specific names of cuneata, ligata, and lata are expressive of charac- 

 ters common to any or all the examples described by Stein, Tatem, Schulze, 

 and myself. 



HYALOSPHENIA PAPILIO. 



Plate XXI. 



Difflugia (Catharia) papilio. Leidy: Pr. Ac. Nat. Sc. 1874, 156. 

 Hijalosphmia papilio. Leidy: Pr. Ac. Nat. Sc. 1875, 415; 1876, 197. 



Shell compressed oblong ovoid, or occasionally compressed pyriform; 

 in the broader view, with the fundus transversely convex and the sides 

 gradually tapering to the slightly convex oral end, or with a pyriform out- 

 line; in the narrower view, with the fundus angularly rounded and the 

 oral end notched. Mouth transversely oval, with rounded commissures. 

 Shell composed of transijarent, yellowish chitinoid membrane. Sarcode 

 with bright green endosarc from the presence of chlorophyl; the mass 



