PLATE XXXIV. 

 Erssea coinvpressa, n. sp. (p. 123). 



(Monogastric generation or free Eudoxia of Diphyopsis compressa, PL XXXIII.) 



Fig. 9. A sessile young cormidium (or an immature Erssea) attached to the stem (a) of Diphyopsis compressa. 

 The cormidium is composed of two sterile medusomes, the first consisting of the bract (b), the 

 siphon (s), and the tentacle (t) ; the second representing a " special nectophore " (mi) ; er, radial 

 canals of the latter ; so, mouth of the siphon ; sb, basigaster ; es, phyllocyst ; co, oleocyst. 



Fig. 10. A somewhat older cormidium than that shown in fig. 9, with larger nectophore (un) and smaller bract (l) 

 detached from the stem. Characters as in fig. 9 ; w, subumbrella of the nectophore ; v, its velum ; 

 un, ostium of the umbrella (u). The bract (b) of this specimen is rudimentary, and its apical 

 cucullate part (with the phyllocyst) is cut off; tk, cnidosacs of the tentacle. 



Fig. 11. A mature and fully developed male Erssea, detached from the stem of Diphyopsis compressa, and 

 swimming freely. The cormidium is composed of four persons, two sterile medusomes and two male 

 gonophores (h). The first sterile medusome consists of a bract (b), a siphon (s), and a tentacle (/). 

 The second sterile medusome is represented by a large " special nectophore " (nn). bs, Superior, 

 cucullate part of the bract, with the phyllocyst (cs) and the oleocyst (cu) ; bz, inferior, mantle- 

 shaped or funnel-shaped, part of the bract, with four basal lobes; st>, mouth of the siphon; sb, basi- 

 gaster; //.', cnidosacs of the tentacle (t) ; lu; cavity of the spadix ; Inn, spermarium. 



Fig. 12. An isolated ripe androphore. Inn, Spermarium ; hx, cavity of the spadix ; u, umbrella; un, its ostium. 



Fig. 13. An isolated ripe gynophore. The manubrium (jm) is filled with large ovules. o\ Nucleolus; </-, 

 nucleus ; o 3 , protoplasm of the ovule ; fp, pedicle ; w, subumbrella ; u, umbrella ; un, its ostium. 



Fig. 14. An older gynophore, the manubrium (Jm) of which contains only four large ovules, cc, Circular 

 canal which connects the four radial canals (cr) ; fp, pedicle of the gonophore ; cp, peduncular canal. 

 The other characters as in fig. 13. 



Fig. 15. A portion of a radial canal (cr) and of the ring-muscles of the subumbrella (//•) of a gonophore. 



Figs. 16, 17. Denticulate edges of the umbrella of a gonophore. 



Fig. 18. A single tentillum, highly magnified, ts, Pedicle ; //, elastic ligament of the cnidosac ; kg, large lateral 

 cnidocysts ; km, small median cnidocysts ; kp, distal pyriform cnidocysts ; tf, terminal filament. 



