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 pseudosagittal 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 oral 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 pseudosagittal 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.
