TRACHYNEJIA DIGIT ALE. 



57 



Trachynema digitale A. Agass. 



Medusa digitalis Fav. Faun. Groenl. No. 361. 1780. 



Ttirris (Circe) flif/ilalis IMoRCii (mm Forbes). Besk. at" Gronl., p. 95. 1857. 



Eirene di<jitale Escii. Syst. der Aeal., p. Do. 1829. 



There is coiLsiderable doubt as to the specific difference of this spe- 

 cies of Trachynema from tlie Enghsh Circe of Forbes, and from the 

 Circe camtschntica of Brandt, the series of young observed at Nahant 

 being the only one which gives us any measure of the changes one 

 species undergoes during its growth. It is evident from the figure of 

 Forbes that the genital organs are but slightly developed ; ui the north- 



Fig. 83. 



western species the only specimens observed were all males, while the 

 only adults of this species oljtained on our coast were females. Tliis 

 question must be left undecided until we have a complete history of the 

 English species. 



The adult medusa (Fig. 81) is characterized by the thinness of the 

 bell, the great size of the gelatinous proboscis, which extends nearly to 



Fig. 81. Adult fpmalp Trarliynoma, seen in profde ; masnified. 



Fig. 82. Actinal view of tlio veil and circular tube of a very young Tracliyncuia. c, c, c, c, 

 tentacles opposite the chyniiferous tiil)es ; greatly magnified. 



Fig. 8.3. Profile view of a part of tlie circular tube to show the folds of the veil, c, one of the 

 peduiuulaled marginal capsules; I, young tentacle ; i', folds of the veil ; somewhat more magnified 

 than Fig. 82. 



NO. II. 8 



