484 PEOF. A. DENDY AND MISS L. M. FEEDERICK ON 
Both dermal and gastral cortices are well developed^ the former about 0'18 
and the latter about O'l mm. thick. Between these lies the chamber layer 
with a thickness of about 1 mm. 
The canal system is " sylleibid," the elongated flagellate chambers, up to 
0'4 mm. in length, opening into wide exhalant canals, which interdigitate 
with the main inhalant canals running in from beneath the dermal cortex. 
Small, scattered dermal pores lead into much narrower inhalant canals, which 
pierce the dermal cortex to open into the wide outer ends of these main inhalant 
canals. 
The collared cells are apicinucleate. 
The skeleton of the dermal cortex consists of tangentially placed triradiates 
of various sizes, beneath which lie the short rays of the subdermal pseudo- 
sagittal triradiates. 
The skeleton of the gastral cortex consists exclusively of rather slender 
triradiates arranged tangentially, which become strongly sagittal (alate) 
towards the osculum, with the oi'al arms extended parallel with the margin of 
the latter. 
The skeleton of the chamber layer consists of (1) the contripetally directed 
rays of the large subdermal pseudosagit1;al triradiates, (2) very large and 
stout subgastral sagittal triradiates, (3) similar triradiates whose paired rays 
lie at a variable distance beneath the gastral cortex, (4) the inner portions of 
the large oxea, whose outer portions project through the dermal cortex. 
Spicules'- — (1) Triradiates of the dermal cortex (PI. 26. fig. Gd) : approxi- 
mately regular, with conical, gradually tapering, sharply-pointed rays, 
measuring from about 0"23 by 0-026 to 0-4 by 0-04 mm. 
(2) Triradiates of the gastral cortex (PI. 26. fig. 6 <?) ; approximately 
regular and more or less strongly sagittal; much smaller on the average than 
those of the dermal cortex, with slender, gradually tapering, sharply-pointed 
rays measuring about 0-21 by O'OIS mm. 
(3) Subdermal pseudosagittal triradiates (PI. 26. fig. 6 c) ; the three rays 
are all different ; the true basal ray^ now forming a false pair with one of the 
orals, is the shortest of the three and straight or nearly so, conical and 
gradually sharp-pointed, measuring, say, 0'21 by 0'026 mm. ; the oral ray 
which forms an apparent pair with the basal is rather longer, measuring, say, 
0'26 by 0*026 mm., and more or less crooked ; the other oral ray, now 
centripetally directed, is much longer and more slender, measuring, snj, 0"5 
by 0'02 mm., perfectly straight and gradually sharp-pointed. 
(4) Subgastral sagittal triradiates (PI. 26. fig. 6 h) ; very large and stout, 
rays conical, gradually and sharply pointed, oral rays often slight!}^ curved or 
crooked, basal ray (centrifugally directed) longer than orals; oral rays 
measuring, say, 0"41 by 0-04 mm., with basal 0*52 by 0'05 mm., but variable. 
(5) More distal triradiates of the chamber layer (PL 26. fig. 6 h) ; not 
sharply distinguishable from (4), but usually with shorter basal rays and 
straighter orals. 
