DIFFLUGIA. 15 



fundus. Common, perhaps an extreme variety of lobos- 

 toma. Size : 112/* to 144// broad, by 60/^ to 80/z high ; 

 mouth 28// to 40//. [This form differs from the pre- 

 ceding species principally by the yellowish color of the 

 shell] 



Hob. Sphagnous swamps. 



Difflugia corona. SYN. : D. corona, proteiformis, Wallich. 



Shell spherical or spheroidal, composed of clear, angu- 

 lar quartz-sand ; fundus with conical spines ; mouth ter- 

 minal, circular, with multidentate or crenulate border. 

 Sarcode colorless or brownish ; pseudopods many. A 

 common form, but one of the most beautiful of the 

 genus. The denticles are thick, angular processes, usu- 

 ally twelve in number, ranging from six to sixteen. 

 The spines range from one to eleven, usually three to 

 seven, arranged in an eccentric circle, divergent, equidis- 

 tant, often a central spine is larger than the others. 

 Size from 140/z to 320/* in diameter ; mouth 60/z to 

 wide ; spines 40^ to 60// long. 



Hob. Marshes, ponds, etc. 



COnstricta. SYN. : Arcella constricta, lunata, Arr- 

 tiscon, guatimalensis , Ehr. ; D. marsupiformis, proteiformis, Wallich ; 

 A. Homaochlamis constricta and htnata, Ehr. ; A. Heterocosmia Arctiscon 

 and g uatimalensis, Ehr. ; A. borealis, laticeps, Ehr. 



Shell laterally ovoid, fundus more or less prolonged 

 obliquely upward, obtusely rounded and simple, or pro- 

 vided with spines. Mouth antero-inferior, large, circu- 

 lar or oval and inverted, with the anterior lip often 

 prominent. Shell as usually seen by transmitted light, 

 lying on the front, more or less pyriform, with the nar- 



