158 



DEPARTMEyr OF THE NATAL SERVICE 



Genus Goxothyr.ea. 



Trophosomc. As in the family. 



Gonosome. Reproduction by lixed niedusiforra sporosaca, furnisbed with ten- 

 tacles, that at maturity become extra-eapsular, remaining attached until their con- 

 tents are discharged. 



KKY TO SPKCIKS. 



a Colony slightly and irregularly branched, margin with sharp teeth. G. gracilis. 

 h Colony large, more regularly branched, margin with blunt, square-topped teeth. 



G. loveni. 



Gonothyi'cca gracilis (Sars). 



Trophosomc. Colony slightly and irregularly 

 branched; stem, branches and ])edicels, long and 

 slender; stem annulated at the base and above the 

 origin of each branch; pedicels annulated at each end; 

 hydrotheca deep, cylindrical for the upper half and 

 gradually tapering to the base; margin with 10-14 

 deeply-cut, sharp teeth. 



Gonosome. Gonangium oblong-oval, often flaring 

 at the rim; on the stem or stolon; pedicel annulated. 



No. 43. 



Gonothyraa gracilis. 



Gonothyrcea loveni (Allman). 



Trophosomc. Stem branched, flexuose, annulated 

 above the origin of the branches and pedicels; pedicels 

 short, annulated; hydrotheca slightly deeper than wide; 

 margin with teeth that are usually square-topped but 

 may be more rounded. 



Gonosome. Gonnngium axillary, obconic, on a 

 short annulated pedicel. 



Genus Obelia. 



No. 44. 

 Go%tothyr(ra loveni. 



Trophosomc. Stem branched, simple or fascicled. 



Gonosome. Gonophores producing free medusae, that are flattened dorso- 

 ventrally and when liberated ]X)Sseps more than eight tentacles. 



KEY TO SPECIES. 



^fargin toothed. 



h Gonangium much shorter than the stem internodes, 

 hh Gonangium usually longer than the stem internodes. 



0. longissima. 

 0. articvlafa. 



aa Margin entire. 



c Hydrotheca pedicels usually forming the only branches. 



d Hydrotheca deeper than wide. 0. dichotom.a. 



dd Hydrotheca as wide as deep. 



e Hydrotheca i>edicel supported on a shoulder-like process of the 

 stem internode. 0. geniculata. 



ee No shoulder present on the stem internode. 0. hyalina. 



cc Stem with other branches than those formed by the hydranth pedicels. 



/ Hydrotheca deeper than wide. 0. commissuralis. 



ff Hydrotheca as wide as deep. 0. flahellafa. 



