.SPONGOZOA. 
565 
globular cells of which become the endoderm, while the ectoderm is 
made up of the flagellate cells. Between both, the intermediate hyaline 
layer is developed. Cf. the remarks of Hack el in his paper on the 
“ Gastrula (Jen. Z. Nat. ix. p. 499, postscript). 
Marshall (14) has found advanced embryos of Hyalonema in the 
larger cavities of the body, and describes (p. 234) their structure. 
Schmidt (17) has observed the formation of gemmules in the substance 
of decaying sponges. A note by H. C. Sorby, “ On the chromatological 
relations of Spongilla fluviatilis ” ; Q. J. Micr. Sci. xv. pp. 47-62. 
Another by Parfitt, “ Does Cliona burrow” ; M. Micr. J. vii. pp. 186-188. 
Distribution y Glassification, Genera, and Sjjecies. 
The Spongozoa of Greenland are registered after Hackel and Oscar 
Schmidt, in the “Arctic Manual,” pp. 190 & 191. 
Carter (6) divides the Spongida into 8 orders, 22 families, and a great 
number of subordinate groups (excluding the Calcar eaD- The cha- 
racters of “ orders” and “families ” are given thus : — 
I. Carnosa. Without evident skeleton. 
1. Halisarcida. No spicules. 
2. Gumminida. Spicules present. 
II. Ceratina. Skeleton composed of horny fibre with a granular, 
chiefly hollow, core, containing for the most part no foreign bodies. 
3. Luffarida. Rigid fibre, with opaque, white, granular core, mostly 
hollow. 
4. Aphysinida. Subrigid or flaccid fibre, with wide hollow granular 
core. 
6. Pseudoceratida, Fibres of (3) or (4) sparsely cored with foreign 
bodies, or passing into a dermal layer of foreign bodies, or of “ pro- 
per” spicules. 
III. PsAMMONEMATA. Skeleton composed of solid fibre more or less 
cored with foreign bodies. 
6. Bihulida. Solid fibre, chiefly without core of foreign objects. 
7. Hircinida. Solid fibre, chiefly cored with foreign objects. 
8. Pseudohircinida. Solid fibre cored with foreign objects and “ pro- 
per ” spicules, sometimes also echinated with “ proper ” spicules. 
IV. Rhaphidonemata. Skeleton composed of horny fibre, with a 
core of “proper” spicules ; spicules chiefly acerate and confined to the 
interior of the fibre. 
9. Chalinida. Digitations solid, vertical, or procumbent. 
10. Cavochalinida. Tubular, vasiform, aculeated, patulous, or com- 
pressed flabellately ; plane and frondose, or dactyloid. 
11. Acervochalinida. Massive clathrous, or compact and isodictyal. 
12. Pseudochalinida. Digitiferous, composed of fibre cored with 
“ proper” spicules and foreign objects. 
V. Echinonemata. Skeleton composed of horny fibre cored with 
“ proper ” spicules internally, and echinated with “ proper ” spicules ex- 
ternally ; spicules chiefly acerate. 
13. Ectyonida. Echinated with “proper” spicules on the fibr6. 
