EXPLANATION OF PLATE XLVIL 



Fig. 



1-5. PoDOCYATHUS DIADEMA, S. K., vol. ii. p. 827. — I, Adult zooid, with tentacles 

 fully extended, X 300 ; 2, zooid with tentacles retracted ; 3, zooid of abnor- 

 mally minute size as compared with that of the lorica, being probably the 

 relict of a recent fissive process ; 4 and 5, successive developmental forms. 



6, 7. Sph^rophrya sol, Mecz., vol. ii. p. 810. — 6, Normal zooid, x 250 ; 7, elongate 

 shape assumed preparatory to division by transverse fission (Mecznikow.). 



8. Hemiophrya crustaceorum, Haller sp., vol. ii. p. 826. — Zooid with numerous 

 ovate gemmules and distal end of pedicle, x 300 (Haller). 



9-14. Hemiophrya gemmipara, Htwg. sp., vol. ii. p. 823. — 9 and 10, Distal end of 

 pedicle, with zooid at 9 bearing as many as eight elongate ciliated gemmules, 

 and at 10 with two subsphaeroidal tentaculiferous embryos, X 200 ; 11-14, 

 phases of development from a free-swimming hypotrichously ciliated embryo 

 towards the parent form (Robin). 



15. Hemiophrya Benedeni, Fraip. sp., vol. ii. p. 824. — Zooid with extended 

 tentacles and distal region of pedicle, x 200 (Fraipont). 



16-22. Dendrosoma radians, Ehr., vol. ii. p. 841. — 16, Erect, slender zoocaulon of 

 young colony-stock, having but three tentaculiferous ramuscules, as delineated 

 by Mr. Thomas Bolton, x 150; 17, luxuriantly developed colony-stock as 

 supplied to the author by Mr. Bolton, the decumbent stolon, st, giving origin 

 to numerous erect, variously branching zoocaula, some of these, as at a, 

 enclosing internally developed ciliated embryos, and others, as at b b, with 

 more minute externally developed reproductive capsules, X ^o; 18, distal 

 region of zoocaula with exogenous germs, that at a having short capitate 

 tentacles, x 150; 19, portion of zoocaulon with enclosed ciliated embryo e, 

 and a portion of the cord-like endoplast, x 400 ; 20, free-swimming ciliated 

 embryo, x 600; 2i, earliest adherent condition of embryo, the cilia being 

 absorbed and short capitate tentacles developed in their place ; 22, 

 more advanced growth of the same embryo, a single short tentaculiferous 

 prolongation being developed at one extremity, x 600. 



