HYDEOID ZOOPHYTES. 33 



DESCEIPTION OF THE PLATES. 



KEY TO THE LETTEEING OF THE PLATES. 



ae., acrocyst ; bl., blastostyle ; c.p., chitinous pellicle ; d., dactylozooid ; gjjh., gonophore ; gth., gonotheca ; 

 gz., gastrozooid ; he., hydrocaulus ; hrh., hydrorhiza ; Mh., hydrotheca ; hyd., hydranth ; 

 m., manubrium ; n., node ; nph., nematophore ; op., operculum ; ov., ovum ; p., perisarc ; 

 rhc, rhizocaulus ; sp., sperm ; sn.c, sub-umbrella cavity ; t., tentacle ; u., umbrella ; z., zooid. 



PLATE I. 



Fig. 1. — Perigonimiis antarcticus growing on Halecivm arloreum (x 2). he. H., hydrocaukis of 

 Halecium arloreum ; hyd., hydranth of Perigonimus ; gph., gonophore of Perigonimiis. 



Fig. 2. — Perigonimus antarctiens $ ( x 20). hrh., hydrorhiza ; m., manubrium of gonophore ; 

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



Fig. 3. — Perigonimus antarcticus ? showing variability (due to contraction) of form of the hydranths 

 ( X 20). he., hydrocaulus ; hrh., hydrorhiza ; hyd., hydranth ; m., manubrium of gonophore ; 

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



Fig. 4. — Eudendrium insigne. Hydranth (x 30). c, collar of deeply staining cells ; p., perisarc. 



Fig. 5. — Stylactis halecii (x 30). Outer region of colony growing on Halecium arboreum; d., dacty- 

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



Fig. 6. — Stylactis Iwlecii ( x 20). Central region of colony growing on Halecium arboreum ; bl., blasto- 

 style ; bl.t., tentaculate blastostyle ; gz., gastrozooid ; he. H., hydrocaulus of Halecium ; hrh. P. & C. 

 hydrorhiza of Perigonimus and Campanularia. 



PLATE II. 



Fig. 7. — Hydractwiia dendritica encrusting Halecium arboreum ( x 10). bl., blastostyle ; gph., gonophore ; 



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

 Fig. 8. — Hijdractinia dendritica. Fragment of rhizocaulus (x 20). bl., blastostyles ; gph., gonophore; 



gz., gastrozooid ; rhc, rhizocaulus. 

 Fig. 9. — Hydractinia dendritica (x 2). Young rhizocauline colony developing from the encrusting 



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

 Fig. ^k.— Hydractinia dendritica, encrusting Halecium arboreum ( x 1). 



Fig. 10.— Hydractinia dendritica. Part of adult rhizocauline colony ( x 1). rhc, rhizocaulus ; z., zooids. 

 Fig. \l.—Tubularia longstaffi, {x 1). 5^;?^., gonophores ; Mt., hydrorhiza. 

 Fig. 12. — Tubularia ralphi ( x 2). 

 Fig. 13. — Tubidaria hodgsoni ( x 1). 

 Fig. IL—Lampra microrhiza ( x 1). c.p., chitinous pellicle ; gph., gonophores ; hrh. /., hydrorhizal 



filaments. 



PLATE III. 



Fig. Ih.—Lampra parvula. Young zooid (x 10). d.t., distal tentacles; he, hydrocaulus; hrh. f., 



hyrdrorhizal filament ; hyd., hydranth ; p.t., proximal tentacles ; P.2.,polyzoan colony to which the 

 zooid is attached. 



VOL. III. ^ G 



