584 Chas. W. Hargitt 



base of teutacles as mentioned abovc; the base of the manubrium 

 is likewise 8lii,^htly brownish. 



As a final note I desire to acknowledge my obligations to the 

 Zoologieal Station for material used in the foregoing descriptions, 

 and my grateful appreciation of the imfailiug courtesy of the Director 

 and other members of the Staff. 



Explanation of Figures. 



Piate 21. 



Fig. 1. Entire colony of hydroid, Pachycorchjie Weismanni. X 3. 



Fig. 2. Medusa of same. Greatly magnified. 



Fig. 3. Longitudinal section of stem and gonophore bud, showing egg-cells 



in entoderm. 

 Fig. 4. Similar section throngh gonophore of later stage, showing bell- 



nucleus Glk. 

 Fig. 5. Similar section of slightly later stage, showing foUicular groups of 



ova, and development of ectoderm of medusa. 

 Fig. 6. Optical section of medusa about the time of Isolation from the 



coenosarc of stem. 

 Fig. 7. Section of mature medusa at time of birth. m. marginal rim; v. velum; 



c.c. circular canal? 

 Fig. 8. Section through medusa bud some time prior to maturity, showing 



nutritive entoderm at mt, various nuclear features, etc. 

 Fig. 9. Section of egg of Tubularia mesemhryanthemtmi , showing multinu- 



cleate condition before cleavage. n. nuclei; ;>.s-.c-. pseudocelis; g.iv. wall 



of gonophore. 

 Fig. 10. Section of an egg similar to fig. 9, with lines of incipient cleavage 



at c.pl. 

 Fig. 11. Later stage of multinucleate agg, syncytium. 

 Figs. 12 — 17. Outlines of first six sections of an egg. only four of which showed 



nuclei. 



Piate 22. 



FigB. 18 — 23. Similar series, median six sections in a series of foiirteen, showing 

 progressive cleavage from animai to vegetai pole. 



Fig. 24. Young jtolyps attached to stem of parent hydroid. 



Fig. 25. Colony of hydroid, rcrigonimus nripolUanus. x 10. 



Fig. 26. Medusa o{ Podocoryw conrhicola, showing position of tentacles during 

 active movements of medusa. 



Fig. 27. Colony of Gemmaria implrra on shell. x 3. 



