12 DAVENPORT ACADEMY OF SCIENCES. 



DINAMCEBA I.eidy. 



Amoeba-like, oval or elongate when active. Pseudopodia usu- 

 ally many. Posterior region with or without short, blunt papillae. 

 Body often surrounded by a zone of transparent protoplasm. 

 Spicules present. 



DiNAMCEBA MIRABILIS Leidy. 



Body somewhat resembling Amtvba proteiis but more regular in 

 outline. Pseudopodia very numerous, long, finger-like, with or 

 without minute lateral processes. 



Length, as observed, 200 microns. (Fig. 5, PI. I.) 



When active, this organism extends pseudopodia from all parts 

 of the periphery and often the body is surrounded by a broad layer 

 of hyaline protoplasm through which the pseudopodia protrude 

 for a considerable distance. This external layer is often marked 

 by myriads of minute spicules which give it a striated appearance, 

 the striae being parallel to the long axis of the pseudopodia. The 

 spicules may or may not be found on the extended pseudopodia. 

 In the forms coming under my observation the posterior papillae 

 were usually entirely absent. 



Dinaiuivba iiiirabilis, is found in pond water. It feeds upon algae, 

 diatoms, etc., the endoplasm often being densely packed with these 

 organisms. 



Family, ARCELIvID^. 



DIFFI.UGIA Leclerc. 



Body protected by a shell which is composed largely of foreign 

 particles, commonly fine quartz sand. Mouth usually terminal, 

 from which maybe extended long, cylindrical pseudopodia, either 

 simple or branched. 



Nine species have been found in the waters of this state. 



DiFFLUGIA PYRIFORMIS Pcrty. 



Shell oval or pear-shaped, sometimes with a short neck and 

 broadly expanded fundus with or without spines, composed 

 mainly of sand grains. Pseudopodia slender, cylindrical, simple 

 or branched. 



lycngth of shell, from 50 to 300 microns. 



This species is a common one and many varieties of shells must 

 be included in it. 



