LEPTOMEDUSAE. 



133 



Fam. 3. Perisiphonidae. Hydrocaulus enveloped by peripheral tubes; the 

 hydrothecae arc never adnate and are carried by the axial tube only. Lafoea 

 Lamouroux ; Lictorclla Allm. ; Cnjptolaria Busk ; Perisiphonia Allm. 



Section 2. Sertularinae. 



Hydrothecae developed from more than one side of the hydrocaulus, to which 

 they are all adnate for a greater or less extent by their sides. 



Fam. 4. Grammaridae. Hydrocaulus consisting of an axial tube which carries 

 the hydrothecae and is sur- 

 rounded by and inseparably 

 coalesced with peripheral tubes 

 without hydrothecae. Hydro- 

 thecae adnate to axial tube. 

 Gramma.ria Stimpson. 



Fam. 5. Sertularidae. Hy- 

 drothecae in two or more 

 series, adnate to hydrocaulus. 

 Gonophores sessile. Scrtularia 

 L. ; Diphasia Agassiz ; Thui- 

 aria Fleming ; Desmoscyphus 

 Allm. ; Hypopyxis Allm. ; 

 Staurothcca Allm. ; Dictyo- 

 cladium Allm. ; Syntliecium 

 Allm. ; Thccocladium Allm. ; 

 Hydrallmania Hincks. 



FIG. 115. Free Medusa of Obdia gdatinosa as yet 

 without gonads ; g otocysts. 



Section 3. Idiinae. 



Hydrothecae adnate to hy- 

 drocaulus. Coenosark divided 

 into segments which form two longitudinal series of intercommunicating cham- 

 bers, each of which communicates with the gastral cavity of a hydranth. 



Fam. 6. Idiidae. Idia Lamouroux. 



Section 4. Plumularinae. 



Hydrothecae developed from one side only of the hydrocaulus, to which they 

 are adnate by their sides. Sarcostyles (nematophores) are always present. 



Fam. 7. Plumularidae. A ntennularia Lamarck; Sciurella Allm. ; AcantheUa 

 Allm. ; Plumularia Lamk. ; Schizotricha Allm. ; Polyplumaria Sars ; Hctcroplon 

 Allm. ; HaUcornaria Busk ; Azygoplon Allm. ; Streptoeaulus Allm. ; Diplocheilus 

 Allm.; Lytocarpus Kirchenpauer ; Acanthocladium Allm.; Cladocarpus Allm.; 

 Aylaophenia Lamouroux. 



The Medusae of this order are arranged by Haeckel as follows : 



LEPTOMEDUSAE. 



Craspedota partly tcitli, partly without, otocysts ; ocelli present or 

 absent ; .gonads on radial canals ; budded from polyps of the 

 Campanulariae. 



Fam. 1. Thaumantidae. Radial canals simple, unbranched, without otocysts. 

 Polyp form known only in Laodicc (Thaumantaria) calcarata as Thaumantias 

 inconspicua, and in Melicertum campanula as Meliccrtum campanula. 



