114 Transactions of the Society : 



attached to the outside of the test; and (2) those formed by a 

 modification and extension of the body-scales. 



In the first group, containing four species, the spines of E. ciliata 

 and E. strigosa (Ehrenb.) Leidy (PI. II, figs. 10-12), are circular in 

 section and taper to a point, with bases cemented to the test ; the 

 spines of E.filifera Penard are similar, but longer, few in number 

 and spaced at equal distances apart on a plane passing through the 

 longitudinal axis of the test ; at the base of each is a small hemi- 

 spherical nodule into which the spine is fixed, its base being 

 somewhat enlarged, thus forming a kind of ball-and-socket joint, 

 enabling the spine to be bent considerably in any direction without 

 breaking away from the test ; the spines of the tests of E. compressa 

 Carter (PI. Ill, figs. 19-24), and of Placocysta spinosa Leidy are 

 attached in a similar manner. It should, however, be noted that 

 it requires a magnification of 1000 or more and favourable condi- 

 tions to reveal this structure, and possibly the movement of the 

 spines may in many cases be due to their being forcibly bent at 

 their base. In the case of the two last-mentioned species the 

 spines are flattened and usually lanceolate, but show considerable 

 variation of form in different individuals. 



In the second group certain scales are prolonged into spines of 

 variable length ; they are usually either around the upper part of 

 the test or form a tuft or crest at its apex, as in E. cristata 

 (PI. II, fig. 8). Euglypha brachiata Leidy has a test noticeable for 

 the long spines originating near the aperture, which are circular 

 in section, tapering gradually to a point ; they are usually two or 

 four in number, but occasionally so many as six or eight are 

 present. In the test of its var. librata Wailes (9) they originate 

 about half way up the test and are flattened at the points, 

 which resemble oar-blades (PI. II, fig. 15) ; their total length is 

 about 35 /x with a diameter of about 1 fx, widening to 2*5/xat 

 the free extremity. 



Euglypha mucronata Leidy has usually a single spine placed at 

 the apex of the test, the terminal scales fitting closely together 

 around its base (PI. Ill, figs. 25, 2(3), but if any interstice remains 

 a small transverse diaphragm is formed just below it ; the spine 

 lies normally in line with the axis of the test, and to ensure this 

 is bent the requisite amount close to the scale which bears it. 



In the genus Cyphoderia a distinct type of test is found, flask- 

 shaped, with a curved neck ; under a moderate magnification it 

 appears densely punctate, but under higher powers its composite 

 structure is plainly visible. Two distinct types of structure occur, 

 one formed of small flat disks cemented together at their edges, 

 and the other of imbricated circular scales ; these disks or scales 

 are often to be seen within the tests of individuals collected in 

 readiness for the building of a new test. C. ampulla Ehrenb. 



