DEVELOPxMENT. 



109 



The reversed spike, or spike with a centrifugal development, shows itself in such forms as 

 Bicoryne conferta (PL VIII, lig. 1, and woodcut, fig. 41) ; while in Laomedca (woodcuts, figs. 18 

 and 48), ObeJia, woodcut, fig. 19), and other calyptoblastic forms, we have a reversed spike 



Diagram ot' Tnhularia indivisa, 



a, a. llydranth with its stalk; b, shortly 

 stalked gonophores, borne on a common 

 peduncle, and increasing in maturity from 

 the proximal to the distal extremity of the 

 pedunrle. 



Fig. 45. 



Diagram of Tnbularia larynx — female. 



a, a. A hydranth with its stalk ; 5, 

 gouophores, attached by short stalks to 

 a common branched peduncle, and in- 

 creasing in maturity from the proximal 

 to the distal extremities of the branches. 



Fig. 46. 



Fig. 47. 



surronncled by the gonangial sheath, and, were it not for its centrifugal development, strongly 

 recalling the spadix with its spathe in the inflorescence of an araceous plant. 



In certain proliferous medusa; (woodcuts, figs. 30 and 37) the buds are borne on the luanu- 

 briuin with a centripetal order of development, thus giving us, according as the buds are sessile 

 or pedunculated, the true spike or the true raceme. 



In Eudcmhium (Pis. XIII and XIV) the male gonophores are disposed in an umbel with 



the axis, in some cases prolonged beyond 



it, while in others there is no extension of 



the axis beyond the depressed portion 



which carries the gonophores. Though 



we cannot here recognise any difference 



in the order of development among the 



gonophores composing the umbel, we are 



probably justified in assuming this order 



to be, as in the true umbel, a centripetal 



one; for in the female colonies of most 



species, such as Eudendrium ramosum 



(PI. XIII, fig. 3), the gonophores are 



separated from distance to distance upon 



the stem immediately below the hydranth, 



and here their order of development is 



plainly seen to be centripetal. 



In Ilijdraclinia echinala (PI. XV, 

 figs. 1 and 3, and woodcut, fig. 4G) we have the closely approximated gonophores sessile on a 

 blastostyle, and the development centripetal, as in the true spike, while the axis extends beyond 



Rydractinia. A blastostyle 

 with gonophores clustering 

 round it, and increasing in ma- 

 turity fi'om the free or distal to 

 the attached or pruxinuil end. 



data. A hydranth surrounded 

 by a verticil of globular clusters 

 of gonophores. 



