ii GNIDARIA ORGANISATION OF SIPHONOPHOEA 113 



D. It consists of (1) one or more gonophores, (2) one siphon with 

 tentacle but without bract, (3) one or more palpons with tentacle but 

 without bract. 



E. It consists of (1) a group of gonophores, (2) a siphon together 

 with a tentacle, (3) one or more palpons without tentacle, (4) several 

 bracts, some of which perhaps belong to the palpons and to the siphon. 



Less frequently we find in the cormidium several siphons with 

 tentacles. 



The cormidia described under A and B can detach themselves 

 from the stem, and only when they are thus free-swimming Eudoxice 

 (A) or Ersctxe (B) do they ripen the sexual products in their gono- 



\ 



' -'Si 



-/ 



. 



( /.'- 



Ly j 



*fA / r ' // .-'.. .y . ., ,'-y 



yi/^ ; / x 5y 



J V * 



FIG. S6. Single Cormidium (Eudoxia) from Praya galea, after Haeckel. ds, Protective or 

 bract ; r, radial canals of the same ; st, portion of the stem ; hy, siphon or gastric peduncle ; t, ten- 

 tacle ; nk, stinging knobs ; sg, gonophore. 



phores. From the fertilised egg a medusoid Siphonophoran larva is 

 then produced, and from this, by budding, comes the polymorphic 

 Siphonanth stock. 



In many Siphonanths the arrangement of the heteromorphic 

 persons in special cormidia is either more or less obscured (e.g. 

 Rhizophysa, several Agalinidcc and Forskalidce) or quite suppressed, so 

 that the persons are irregularly distributed on the stem (PhysaMa, 

 Agalmopsis). In this case the persons are generally appendages, in 

 which, apart from the gonophores standing in groups or clusters, the 

 medusoid structure is more or less completely degenerated : i.e. siphons 

 with tentacle, taster with or without sensory filament, or isolated 

 bracts. 



This dispersed arrangement is to be explained in this way : the 

 parts belonging to a sterile person, such as siphon or taster, bract or 

 tentacle, become detached, and move away from each other, and stand 



VOL. I I 



