20 THE VOYAGE OF H.M.S. CHALLENGER. 



Subgenus 2. Thalassicollidium, Haeckel. 



Definition. Membrane of the central capsule areolated, with small polygonal plates, 

 resembling an epithelial cell-tissue, spotted by innumerable fine radial pores. 



4. Thalassicolla australis, n. sp. 



Spherical body nearly transparent, without dark pigment. Central capsule colourless, some- 

 what opaque, with a thick and firm, very elastic membrane, areolated by polygonal, punctated figures 

 resembling cells. Diameter of the central capsule about three times that of the nucleus, one- 

 third that of the jelly-cover. Nucleus thin-walled, with many small nucleoli. Protoplasm of 

 the central capsule finely granulated, containing numerous hyaline globules (vacuoles ?) of different 

 size, and in each of these one single roundish, dark refringing corpuscle, concentrically lamellated 

 like an amylum grain. Extracapsular body without pigment or oil-globules, only composed of the 

 large alveoles imbedded in the jelly-cover, and of the fine protoplasmic network between them. 

 No xanthellae. 



Dimensions. Diameter of the central capsule 1 to 2, of its nucleus 0'3 to 0'4, of the nucleoli 

 012 to 0'16, of the hyaline globules in the protoplasm of the capsule 0'02 to 0'05 ; calymma, 

 4 to 6 mm. 



Habitat. South-west Pacific, east coast of Australia, New Zealand, &c. ; Challenger Stations 

 163, 171 ; surface. 



5. Thalassicolla nucleata, Huxley. 



Thalassicolla nucleata, Huxley, 1851, Ann. and Mag. Nat. Hist, ser. 2, vol. viii. p. 435, pi. 



xvi. fig. 4. 



TJialasfticolla nucleata, J. Miiller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 28. 

 Thalassicolla coerulea, Schneider, 1858, Archiv f. Anat. u. Physiol., p. 40, Taf. iii. Bd. i. figs. 5-7. 

 Thalassicolla nucleata, Haeckel, 1862, Monogr. d. Eadiol., p. 249, Taf. iii. figs. 1-5. 

 Thalassicolla nucleata, E. Hertwig, 1876, Histologie d. Eadiol., p. 43, Taf. iii. figs. 61-5, 



Taf. iv., v. 

 Thalassicolla nucleata, R. Hertwig, 1879, Organismus d. Eadiol., p. 34. 



Spherical body in the central part opaque, black or dark coloured, in the periphery transparent, 

 whitish, or yellowish. Central capsule rather compact, yellowish, opaque, with a thick and firm, 

 very elastic membrane, areolated by polygonal, punctated figures resembling cells. Diameter of 

 the central capsule about twice as large as that of the nucleus, one-half to one-fourth that of the 

 jelly-cover. Nucleus with a very thick, finely punctated membrane, containing a viscous fluid (when 

 coagulated finely granular), and sometimes one large, central, spherical, or ramified nucleolus, some- 

 times a variable number of smaller roundish nucleoli. Protoplasm of the central capsule containing 

 many very variable corpuscles, mostly pellucid (albuminous ?) spherules, containing oil-globules, or 

 concentric amyloid concretions, or crystals, &c. Extracapsular body with dark pigment-powder of 

 variable colour (black, brown, violet, blue, &c.), densely aggregated around the central capsule, more 

 loosely dissipated between the alveoles of the outer jelly-cover. Xanthellae very numerous. 



