300 E. PENARD ON SOME RHIZOPODS FROM SIERRA LEONE. 



were small varieties ; Euglyjjha alveolata much smaller than the- 

 type ; and as for Euglypha laevis, or what I considered as such^ 

 it was very thin and inconspicuous, and I could not arrive at 

 a definite conclusion about it. Of Difflugia constricta there 

 were two varieties, both with elongated tests ; a typical Difflugia 

 acuminata was found, but two other forms existed also var. 

 inAata Penard, and a very short, nearly spherical and sharply 

 pointed variety. Pontigulasia vas was a variety, or rather there- 

 were two varieties, both extremely small. 

 Much more curious are the following : 



? Centropyxis arcelloides Penard (PI. 9, Figs. 1, 2). 



Only when making allowance for a very large amount of 

 specific variability could the Sierra Leone specimens be considered 

 as belonging to this species ; in fact, they might represent some- 

 thing else, autonomous types ; and not only one, but two species- 

 rather than one, for the tests very numerous but always empty 

 could be found under two different aspects, and without any 

 transition between them. 



Fig. 1 shows the first of these forms, flat discs, where, as a 

 rule, no opening could be detected, and which hardly looked like- 

 the test of a Rhizopod. A further examination, however, showed 

 a dorsal and a ventral aspect, this latter slightly invaginated, 

 and provided with a narrow central opening. The tests, 187 tO' 

 209 fx broad, were composed of small fiat sand particles imbedded 

 in a colourless chitinoid material. 



The second form (Fig. 2), with a test of the same structure,. 

 was much larger, 330 to 380 fx in diameter, with a higher, 

 regularly convex dome, and a flattened ventral face ; the central 

 orifice was very large, more than half the entire breadth of the- 

 shell, and with a distinctly crenulated margin. 



Pontigulasia compressa (Carter) Cash (PI. 9, Fig. 3). 



This species was fairly well represented, but the specimens, of 

 a larger average size than the type (200 to 220 fx, instead of 

 about 100), and which in fact might as well have been referred 

 to that big lacustrine form which was described as Pontigulasia 

 higihbosa Penard, showed a peculiar appearance, which seeras not 

 to have been noticed anywhere before. 



