171 



appear as narrow incisions, which join the zooecial aperture, and the short po- 

 lypide-tube, which is not continued under the cryptocyst cover, is in most cases 

 provided with marginal flanges. Avicalaria are always present and sometimes 

 hyperstomial ooecia, on each side of which we generally see a compressed, higher 

 or lower process. The distal wall as well as the lateral walls may have some- 

 times uniporous, sometimes multiporous rosette plates. 



Synopsis of the genera. 



1) Ooecia occur, on each side of which a compressed process is 

 generally seen; no distinct raised margins; frontal wall of polypide- 

 tube quadrangular or trapeziform, surrounded by more or less strongly 

 projecting flanges Aspidostoma Hincks. 



1) No ooecia; distinct raised margins; frontal wall of polypide- 

 tube not quadrangular and not surrounded by projecting flanges: 



2) Polypide-tube bilabiate, on either side connected with the 

 lateral wall by a vertical calcareous lamina; multiporous rosette- 



P'^^^^ Labiopora n. g. 



2) Polypide-tube not bilabiate, with an expanded distal margin, 

 not connected with the lateral walls by vertical calcareous laminae; 

 uniporous rosette-plates Crateropora n. g. 



Aspidostoma giganteum Busk. 

 Eschara gigantea Busk, Catalogue of Marine Polyzoa, Part I, Cheilostomata, 



pag. 91, PI. CXIX, fig. 3. 

 Aspidostoma crassum Hincks, Annals Nat. Hist. ser. 5, Vol. 7, pag. 160, PI. X, 



figs. 6, 6 a. 

 Aspidostoma giganteum Busk, Challenger Zoology, Vol. V, Part I, pag. 161, 



PI. XXXIII, fig. 3. 

 — — Jullien, Bryozoaires, Mission du Cap Horn, pag. 77, 



PI. 6, figs. 5—6. 

 Aspidostoma gigantea Waters, Challenger Zoology, Vol. XXXI, pag. 28, PI. I,, 



figs. 16—18, PI. III,. figs. 20, 21. 

 Micropora cavata Waters, Quart. Journ. Geol. Soc, Vol. XXXIX, pag. 435. 



(PI. VI c, figs. 2 a-2 d). 



The zooecia, which may attain a length of up to 1.5 mm., are typically 

 feexagonally lyre-shaped, but often of a rather irregular form. They are very Ihick- 

 walled, almost without pores and provided with a close reticulation of small 

 tuberculated ridges. They attaiii their greatest height in the strongly projecting 



