848 SIDN15Y F. HARMKR. 



Fig, 10.— Scliizopoic.lla saiisn i'lea, Norm. — IJasal view of a zoiccium 

 rioiii wliicli I lie basal wall lias been leiiioved. — Naples. 



Fig. 47. — Schizoporella australis, llaswell. 0|)eiculuiii with llie ileii- 

 liculated coiid.yles. — Torres SUails. 



Fig. IS. — Scbizoi)orella linearis, Uassall. Siiowiiig- ^/y/c, a gigantic 

 aviculariuin (=: " ooecium," Hincks) ; prux., jiroxinial eml ol' liie zuoeciuni, inio 

 which the poly|)ide extends, beneath the aviculariiun. — Na|)lcs. 



Fig. 49. — Catenaria lafontii, And. Side view, showing llie conipcn- 

 sation-sac ; z.', daughter-zooecia. — Naples. 



Fig. 50. — Uiagranimalic transverse section of an Unibonuloid Cheilostonie . 

 The cavity of the marginal areolae [ar.) communicates with the general body- 

 cavity by the pores p. ; /'. sh., frontnl shield, with calcareous tubercles on its 

 outer surface ; ep., epitheca ; /. vi., frontal membrane, or floor of compensation- 

 sac (c. s.). 



Pig. 51. — Diagrammatic obliquely transverse section through a Microporoid 

 Cheilostonie, passing on the right side through the horizontal })art of the 

 cryptocyst [crypt.), and on the left side through a lateral recess (/. r.) con- 

 taining a depressor muscle {(lepr.) or modified parietal muscle ; y. ??«., frontal 

 membrane (cf. PI. 18, fig. 58). 



Fig. 52. — Schizo[)orella linearis, Hassall. Zooecium showing the com- 

 pensation-sac {c. s.). The emarginal ion of the frontal shield containing the sinus 

 of the operculum enlarges as it passes through the thickness of the calcareous 

 wall, so that its outline on the inner side of the frontal shield is represented 

 by the line x. — Na))les. 



PLATE 18. 



F'ig. 53. — Cateniceila alata, Wyv. Thonis. The zooecium, which forms 

 the median part of the "globulus," is overlaj)ped by the lateral wings, con- 

 stituted by sttp. uvic, the supra-avicularian compartment; acic, the vestigial 

 avicularium ; and inf. avic, the iiifra-avicularian conii)artinent ; .i\ edge of 

 calcareous plate corresponding with pi. in Fig. 51. — Victoria. 



Fig. 5 t. — C. i)lagiostoma, Busk, var. setigera, MacGill. The avicu- 

 laria are here of enormous size, and are different on the two sides of the 

 gloljulns. The roof of the com|)ensation-sac {c. s.) is partly a calcareous 

 plate ip/.) coiuiecled with the calcareous framework of the operculum; the 

 free edge of this plaie is seen at x. The outer calcareous layer consists of a 

 system of narrow bars sejjaratcd by large ineinbranous I'enestric {/.). — Vic- 

 toria. 



Fig. 55. — C. hastata, Jnisk. 'I'he avicularium {(tvic), although small, 

 possesses a rudimentary polypidc (puL). The infra-aviculaiian compartment 

 {u/f. iicic.) is completely divided into two parts, of whieh the lower appears to 



