PLATE XVI. 



PODOCORYNE CARNEA, HyDRACTINIA ECHINATA. 



Fig. 



1. Portion of a colony of PoJoconjne carnea, magnified; a, a, a, sterile hydrantlis in various 



states of contraction ; b, b, proliferous hydrantlis laden with planoljlasts, the planoblasts 

 in various stages of development. 



2. A colony of Podocoryne carnea, natural size, spreading over the surface of a piece of 



submerged rock. 



3. A planoblast just after its lil)cration from the trophosome floating in the water, and with 



its tentacles extended. 



4. The same with its tentacles contracted and thrown up round tlie margin of tlie umbrella. 



5. Planoblasts in the act of swimming seen at the moment of systole, the umbrella strongly 



contracted and assuming a conical form. 



6. A free planoblast more magnified, floating in the water, and with its tentacles extended. 



7. One of the oral lobes of the manubrium of the planoblast showing its pencil of stalked 



thread-cells. 



8. Portion of the umbrella-margin of a planoblast ; a, marginal tentacle ; b, a radiating canal ; 



e, circular canal; d, ectoderm of margin, where it forms a cushion-like thickening on the 

 bulbous root of the tentacle; c, ectoderm continued round the extreme margin of the 

 undu'clla. 



9. A [)ortion of the common basis of a young colony, showing its coalescent chitinous tubes. 



10. Ilj/dractiuia echinata, vertical section through the common basal expansion extending from 



the free towards the attached surface ; some of the coalescent chitinous tubes filled with 

 ccenosarc, others empty ; «, «, superficial layer of ectoderm extending over the free 

 surface ; b, cocnosarcal tube lying in one of the superficial chitinous channels ; c, c, walls 

 of the adnate chitinous tubes ; % proximal extremity of a hydranth, its cavity continuous 

 with that of one of the ccenosarc tubes of the common basis. 



11. Portion taken from the edge of the basal expansion in a colony of ITijdractinia echinata, 



where it had been injured and is undergoing reparation ; the chitinous tubes, with their 

 cocnosarcal contents, are seen extending themselves in the form of a network, the meshes 

 of which subsequently become obliterated by the coalescence of the chitinous walls. 



