APPENDIX TO CHAPTER XIV 221 



61. Hydroids present ; medusae without free 



auditory clubs. 



Ci. Hydroid stocks, with calcareous ex- 

 ternal skeleton ; no free medusae . Hydrocorallidce 

 Co. Hydroid heads never enclosed in cuticu- 

 lar cup ; medusae, if free, without 

 marginal vesicles ; gonads on manu- 

 brium ...... Tubularities 



c 3 . Hydroid heads enclosed in calyx ; me- 

 dusae, if free, with gonads on radial 



canals Campanularidce 



b-2- Hydroids absent ; medusae with free-stand- 

 ing auditory clubs. 



GI. Gonads on radial canals . . . Trachomedusas 

 Cz- Gonads on manubrium . . . Narcomedusas 



