LITTLE-KNOWN BRITISH EHIZOPODS. 83 



might be identified with E. hryophila, but he makes no reference to this form 

 in his later works. 



Placocysta jurassica, Penard. (Plate 9. figs. 16-18.) 

 Penard, in Revue Suisse de Zool. 1905, p. 611, tigs. 29 & 30. 



This species has not previously been reported from England *, It occurred 

 in comparatively small numbers in sphagnum gathered near Harrop Tarn 

 (Cumberland) in May 1910. and again in sphagnum obtained near Stranraer 

 (Wigtownshire) in September 1910. 



P. jurassica differs from the more common P. spinosa, Leidy, in its 

 smaller size (72-76 /i), its greater breadth in proportion to its length, its less 

 compressed form, and especially in the character of its spines. These are 

 not restricted to the margins of the test as they are in P. spinosa, but are 

 distributed over its whole surface, though less numerous towards the middle 

 of the broad faces. In form they are not broad flattened blades, but are fine 

 " cils " like those of many species of Evglyplia. They arise from the test at 

 the points of junction of three plates (PI. 9. fig. 18). (Penard's figure shows 

 some of the spines arising from the middle of the plates themselves. This I 

 have never seen.) At such points the cementing material is thickened in the 

 form of a raised ring, in the central depression of which the " cil " is 

 implanted. These rings appear as dots under low magnification, but under 

 the higher powers their real character is demonstrated. Each ring would 

 represent " le coussinet chitineux,"' which Penard describes in P. spinosa. 

 In places, two or three spines arise together and then two or three annular 

 formations occur in juxtaposition. The plates are much less regularly 

 arranged, and are comparatively smaller and more numerous, than in 

 P. spinosa. None of the individuals found w^ere active. 



Sphenodeeia macrolepis, Leidy. (Plate 9. fig. 19.) 



Leidy, ' Fresliwater Ehizopods of N. America,' 1879, p. 232 and text-fig. 



So far as I have been able to discover, no records of this species occur 

 since Leidy's time. It must be one of the rarest species of Rhii^opod. 



Several individuals occurred, however, in sphagnum gathered near 

 Stranraer (Wigtownshire) on September 1910. They are quite characteristic 

 and cannot be confused with any other species. 



Leidy describes the test as compressed, with a broad neck graduallv 

 extending from the body and terminating in the oblique elliptical mouth. 

 The broad faces are occupied mainly by a pair of large hexagonal plates, 

 from which the neck extends below. 



* I find that Mr. W. Evans, in liis Presidential Address to the Roy. Pliys. Soc, Edin. 

 1906 (published 1909), notes P. jurassica as found by Mr. J. Cash in sphagnum from the 

 Pentland Hills. 



LINN. JOURN. — ZOOLOGY, VOL. XXXII. 8 



