dkpartme;nt of marine; biology. 137 



flowing tide-water. But undoubtedly the thecate forms are as abundant as 

 the athecate ones, Campanularidas and Halecidse being as abundant as Phimu- 

 laridse ; while the gymnoblastic hydroid groups are represented by but a few 

 species. No members of the genus Tnbularia were found, nor of the Cory- 

 nidge except Zanclea. 



The following tentative list of identified hydroids can be given : 



Gymnoblast^ : 



Zanclea gemmosa (McCrady), gonosome and medusa. 

 Pennaria; one species (probably not gibbosa Agassiz). 

 Budendrium carnetim Clarke, male, female, and gonosome. 



"Eudendrium" hargettii Congdon (discovered 1906, Bermuda), male, female, and 

 gonosome. 



Campanularid^ : 



Clytia bicophora, gonosome, medusa. C. noliformis, gonosome. 



Obelia dichotoma, gonosome, medusa. O. (commissuralisf) , gonosome, medusa. 



Other Obelidse not yet identified. 

 Campamtlaria ficxuosa (Hincks), female capsules. C. calceolifera, medusa. C. 



minuta. C. amphora Agassiz, gonosome. C. insignis Allman, female capsules, 



hydranths, dredged. C. {edzvardsii?) Nutting. 

 Halecium sessile. C. {articulosuni ?). C. markii Congdon, female (?), and male 



capsules, hydranths. Other Halecidae, not identified. 

 Thyroscyphus ramosus Allman, dredged. 



Plumularid^ : 

 Statopleaii: 



Aglaophenia minuta Allman. A. lophocarpa Allman. A. perpusilla (.'). A. 



contorta Nutting. A. mammillata. A. rhynchocarpa. 

 Lytocarpus philippinnus. 

 Bleutheroplean: 



Plumularia Horida {?). E. cefacea Ellis. E. inermis. E. alternata Nutting. 



Others of this genus not identified. 

 Monotheca margaretta Nutting. 



Monostaechas (quadrideiis ?) or some related species. 

 Halopetris carinata. And others. 



Sertularid^ : 



Sertularia {rathbtini). S. tumida. S. versluysii, gonosome. Several of this genus. 

 Sertularella distans. 



Pasythea quadredentata. Variety with 3 to 4 pairs thecal to each node. 

 Diphasia digitalis. 



While I do not consider this list either as complete or as certain, until fur- 

 ther study of the collection, it includes a variety of genera and species divided 

 among four great groups of hydroids, such as to form a basis for future 

 study of Tortugas hydrozoa. 



Zanclea gemmosa, heretofore recorded from Charleston, and from Woods 

 Hole, Massachusetts, is not the Zanclea found previously at Tortugas by Dr. 

 Mayer, and named Z. gemmosa. That hydroid has the tentacles arranged in 

 whorls, while the gonophores bud from below the proximal whorl. In the 

 specimens I found, the tentacles were truly "scattered," neither spiral nor 

 whorled arrangement being observed in hundreds of specimens examined. 

 The gonosome arises proximally, but often above 3, 4, or more tentacles, and 

 the lack of the heavy perisarc is evident at the base of the hydranths. 



The medusae in the two forms, Zanclea implexa and Z. gemmosa, seem to 

 be identical, and agree with the Woods Hole and English form. 



