10 PORTER [VoL. XIV. 
close-set, and of so nearly uniform height, that in longitudinal 
sections, optical or actual, they have the effect, especially with 
low powers, of a very thick cuticular covering, as thick as the 
ridges are high. But the real thickness of the cuticula is only 
a very small fractional part of the height of the ridges, and is 
therefore many times less than the apparent thickness of the 
cuticula. That this relation of cuticula and contractwe fibres is 
not an accidental or variable one is shown by the fact that the 
cuticula is not of uniform thickness, but presents at regular 
intervals, strictly correlated with its relation to the muscle 
fibres, longitudinal thickenings. These thickenings correspond 
with the crests of the ridges, and the middle of each thickening 
is raised into a sharp ridge (PI. III, cw, Figs. 41, 42). On focus- 
ing with a high power a little above the level of the bottom of 
the furrows, the surface of the gregarine appears striated longi- 
tudinally (Pl. III, Fig. 43), granular stripes alternating with nar- 
rower clear ones. The clear stripes are caused by the depressions 
between the ridges; the darker granular stripes are optical 
longitudinal sections of the subcuticular substance of the 
ridges. At a slightly deeper focusing are seen fine, parallel, 
transverse markings much nearer together than the longitudinal 
stripes; these are due to the very fine, highly refractive circu- 
lar muscle fibres (Pl, III, wu, Fig. 43). In cross sections these 
circular fibres (Pl. III, Figs. 41, 42, mz) can be seen running 
entirely around the parasite, stretching in succession from the 
cuticula at the bottom of one furrow to that at the bottom of 
the next. When the muscles are relaxed the ridges become 
low, rounded, and blunt (Pl. III, Fig. 41); but upon the contrac- . 
tion of the muscles the furrows become narrower and deeper, 
and the ridges higher and more pointed (Pl. III, Fig. 42). 
The protomerite of this gregarine has the form of a biconvex 
lens set in a corresponding depression of the anterior end of 
the deutomerite (Pl. III, Figs. 44, 46, pr’mer). It is composed 
of a very compact and finely granular protoplasm. The anterior 
portion is slightly denser and more deeply stained than the 
posterior half. From the centre of its anterior surface the 
epimerite (PI. III, Figs. 44, 46, e’mer) arises as a conical structure 
tapering off at its anterior end into a long filament (//). 
