171 



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

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

 [)rovided with marginal ilanges. Aoiculaiia are always present and sometimes 

 hyi)ersloniiai ocrcia, on each side of which we generally see a compressed, higher 

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

 limes uniporous, sometimes multiporous rosette plates. 



Synopsis of the genera. 



1) 0(L'cia 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 Ilanges Aspidostoma Hincks. 



1) No oo'cia; distinct raised margins; frontal wall of polypide- 

 tuhe 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- 

 plates Ldbiopora n. g. 



2) I'olypide-tube not bilabiate, with an expanded distal margin, 

 not connected with the lateral walls by vertical calcareous laminae; 

 uniporous rosette-plates ■ ■ ■ CrateropoVa n. g. 



Aspidostoma giganteum Busk. — f^/ft Vf_C . A?J $A-2f 

 Eschara giganlea Husk, 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. 1, 



figs. 16—18, PI. Ill, 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 

 hexagonally lyre-shai)ed, but often of a rather irregular form. They are very thick- 

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

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



