REPORT ON THE TETRACTINELLIDA. 
417 
Family I, Axinellid^(0. Schmidt). 
The ectosome is not a cortex, the mesoderm of the choanosome is collenchymatous, 
the chamber-system is eurypylous. The skeleton consists of axial fibres and radial 
fibres proceeding from them to the surface. The megascleres are styles and rhabdi, 
which may be isoactinate or anisoactinate, or both. The microsclere when present is a 
spheraster or oxyaster or strongylaster (in one genus, Tricentrium, the aster is sometimes 
a microcalthrops). 
Genera. 
1. Hymeniacidon (Bowerbank), Ridley and Dendy, loc. cit., p. 166. 
2. Phacellia (Bowerbank), Ridley and Dendy, loc. cit., p. 169. 
3. Ciocalypta (Bowerbank), Ridley and Dendy, loc. cit., p. 173. 
4. Acanthella (0. Schmidt), Ridley and Dendy, loc. cit., p. 176. 
5. Axinella (0. Schmidt), Ridley and Dendy, loc. cit., p. 178. 
6. Raspailia (Nardo), Ridley and Dendy, loc. cit., p. 188. 
7. Dendropsis, Ridley and Dendy, loc. cit., p. 191. 
8. Thrinacophora, Ridley and Dendy, loc. cit., p. 193. 
9. Dictyocylindrus, Bowerbank, Mon. Brit. Spong., vol. iii., pi. xix. figs. 1—7, 
vol. ii. p. 116. 
10. Epallax, n. gen. 
Family II. D OEYPLERID^. 
The ectosome is not a cortex, and the choanosome not regularly folded, the meso- 
derm is collenchymatous. The megascleres are oxeas arranged without order. The 
microsclere is a large oxyaster. 
Genus 1. Dorypleres, n. gen., with a single sj^ecies, Doryplcres dendyi. 
Family III. Tethyid^, Vosmaer. 
The ectosome is a well- differentiated cortex with a distinct fibrous layer. The 
megascleres are strongyloxeas, radially arranged. The microscleres are spherasters, but 
other forms of euaster are frequently present. 
(ZOOL. CHALL. EXP. — PART LXIII. 1888.) 
Err 53 
