HYDROID ZOOPHYTES. 33 



DESCRIPTION OF THE PLATES. 



KEY TO THE LETTERING OF THE PLATES. 



iic., aerocyst ; />/., blastostyle ; *'.j>., chitinous pellicle ; d., dactylozooid ; yph., gonophore ; ylli., gouothcca ; 

 gz., gastrozooid ; he., hydrocaulus ; /irlt., bydrorhiza ; hth., hydrotheca; hyd., hydrantli ; 

 in.., manubrium ; H., node ; nph., nematophore ; op., operculum ; or., ovum ; p., perisare ; 

 /Ac., rhizocanlua ; sp., sperm ; su.c., sub-umbrella cavity ; /., tentacle ; it., umbrella ; z., zuoid. 



PLATE I. 



FIG. 1. Perigonimus antarctic us growing on Halecium arhoreum (x 2). he. H., hydrocaulus of 

 Halecium arbare um ; hyd., hydrauth of Periijonim its ; f/ph., gonophore of Peru/animus. 



FIG. '2. Perigonimus antarcticus $ (x 20). A/7/., hydrorhiza; m., manubrium of gonophore; 

 p., perisarc ; sp., sperm filling the sub-umbrella cavity ; H., umbrella wall. 



FIG. :'.. Perigonimus antarcticus 5? showing variability (due to contraction) of form of the hydranths 

 (x 2n). Ac., hydrocaulus; lirh., hydrorhiza; hyd., hydrauth; m., manubrium of rouoplmiv ; 

 ov., ova embedded in the ectoderm of the manubrium ; si/.c., sub-umbrella cavity ; //., umbrella wall. 



Fn;. 4. Eudeudrium insiyne. Hydranth (x :!((). c., collar of deeply staining cells ; j>., perisarc. 



FII;. 5. -Styliti'tis holer ii (x 3d). Outer region of colony growing on Halecium arboreum ; d., dacty- 

 lozooid ; Ac. H., hydrocaulus of Halecium ; hrh., hydrorhiza ; gz., gastrozooid. 



FIG. (i. Stylactis Italeeii ( x 20). Central region of colony growing on Halecium arhoreum ; hi., blasto- 

 style ; bl.f., tentaeulate blastostyle ; gz., gastrozooid ; Ac. H., hydrocaulus of Halecium ; hrh. P. &. C. 

 hydrorhiza: of Perigonimus and Campanularia. 



PLATE II. 



FIG. 7. Hydractinia dendritica, encrusting Halfdum arloreum (x Id). bl., blastostyle ; gph., gonophore ; 



gz., gastrozooid ; r.sp., ridge-like spine. 

 FIG. 8. Hydractinia dendritica. Fragment of rhizocanlns (x 20). II., blastostyles ; gph., gonophore; 



gz., gastrozooid ; rhc., rhizocaulus. 

 FIG. !>. Hydi-aetinia dendritica (x 2). Young rhizocauline colony developing from the encrusting 



basal region ; enc. r., encrusting region ; fr. rhc., free rhizocauli. 

 FIG. !U. Hydractinia dendritica, encrusting Halecium arboreum (x 1). 



FIG. 10. Hydractinia dendritica. Part of adult rhizocauline colony (x 1). r/jc., rhizocaulus ; .., zooids. 

 FIG. 11. Tubularia longstaffi (x 1). yph., gonophores ; ArA., bydrorhiza. 

 FIG. 12. Tubularia ralphi (x 2). 

 FIG. 13. Tubularia hodysoni ( x 1). 

 FIG. 14. Lampra microrhiza (x 1). c.p., chitinous pellicle; gph., gonopliores ; hrh. f., liydrorhizal 



filaments. 



PLATE III. 



FIG. 15. Lampra pnrvula. Young zooid (x Id). d.t., distal tentacles; Ac., hydrocaulus; hrh. f., 

 hyrdrorhizal filament ; hyd., hydrauth : p.t., proximal tentacles ; /'.:., polyzoan colony to which the 

 zooid is attached. 



VOL. III. - ' 



