AMERICAN HYDRiims. 



exactly intermediate between that of -V. <v>////</, ,/w and the ordinary gonophore, su.-h as is found 

 in Sertularia jnn/i!l(i, for instance. 



... klst 



98 



THE GON080MK OF DIPHAHIA. 



(Figs. 81 and 92 after Allman.) 



Fig. 91. (ionangium of Dijiliax/n nwirru. >-u/ , lobe of co-nosarc extending upward into the gonangial leaf, ft I: yon, gonophore: f] w, gonan- 

 gial wall; or, ova in the "marsupial chamber." Other letters as in preceding figures. 



Fig. 92. Same species; a ymmgcr gonophore, showing curlier stage in the 1'ormalion nf the gmmngial U-avcs. 



Fig. 0:1. /'/y/m.vm/u//'Mv a very yimng gonanginm, showing the hlastostyle entering with a comparatively large ovum at its summit. 



Fig. '.!!. Same species; a somewhat older gonophore, showing optical longitudinal section (schematic) with ova in emlc'dcrm of stem. 



Fig. 95. Same species; a young gonanginm before the development of the gonangial leaves, c, convex summit of gonanginm. 



Fig. %. Same species; young gommgium in which the gonangial leaves are forming, viewed from above, o, small, round opening in 

 summit of the original top of the gonangium. 



Fig. 97. Same specie--; a semidiagraniatic Inntritndinal section, showing the formation of the "marsnpium;" i' '/-, inner wall of gonan- 

 gial Iraf; ti\ outer wall uf guna light 1 leaf; o, opening in the original tuj. of tin- u'nnanginm; !>, plamiht. 



Fig. 9K. Same species; longitudinal section of a male gonanginm, showing two gonophores with spermaries. 



A very simple male gonangiuin is found in ThjJraUiniinia ftilcatu (figs. 88, 90, 111), where 

 the axis of the blastostyle, composed of endodcrmal cells, constitutes a simple spudix around 

 which the sperm cells grow in a mass, the outside of the mass being covered with ectoderm. 



