342 The Philippine Journal of Science i»ia 



E. dispar Agassiz and by Allman ('72) for E. insigne Hincks.* 

 They differ from those described by Congdon ('06) and others 

 for E. ramosum in that the spadix is never recurved or bifur- 

 cated. There are no orthospadicious gonophores found in this 

 species, although the ova from the regular streptospadicious 

 gonophores which become imbedded in the perisarc of the 

 pedicels of atrophying hydranths have a superficial resemblance 

 to that type of gonophore. 



The process by which this deposition of the ova on the pedicel 

 takes place seems to be somewhat as follows: The endodermal 

 tube of the gonophore relaxes ; whether from death of the tissues 

 or because of some stimulus afforded by the results of atrophy 

 in the hydranth was not determined. This relaxation allows the 

 whole weight of the ovum to rest on the ectodermal covering. 

 This layer, probably weakened by lack of nutrition due to the_ 

 atrophy of the hydranth, is unable to support the weight and 

 breaks away. This allows the tube, with the ovum on its inner 

 surface, covered with the mesoglcea and remnants of the ectoderm, 

 to hang down along the pedicel (Plate I, fig. 3). The pressure 

 of the ovum against the pedicel forms a depression in the 

 perisarc (Plate II, fig. 4), and, the mesoglcea becoming attached 

 to the perisarc, glues the ovum in position. The perisarc then 

 becomes thickened at this point, the endodermal tube dis- 

 integrates, and we have the ovum firmly attached to the perisarc 

 of the pedicels (Plate I, fig. 4). Upon -superficial examination 

 this imbedded egg might be mistaken for a form of orthospa- 

 dicious gonophore like that found in E. ramosum, but my material 

 furnishes specimens showing all the stages in the process de- 

 scribed, and I have been unable to find any orthospadicious 

 gonophores. 



That this process is due to the early atrophy of the fertile 

 female hydranths and the necessity of giving the ovum some 

 place of support during fertilization and the early stages of 

 development is the only explanation which seems to be plausible. 

 The fact that in most cases when the ovum is so placed on the 

 pedicel the hydranth has either entirely disintegrated or is be- 

 ginning to show signs of disintegration gives a strong basis for 

 this supposition. 



The male gonophores of E. griffini are not borne in verticils 

 as is usually the case in this genus, but in a single pair on 

 opposite sides of the hydranth near the distal end of the hy- 



• Figured by Allman in his Monograph on the Tubularian Hydroids under 

 the name E, humile Allman. 



