vol.i.] Torreij. — Hydroida of the Pacific Canst. 21 



42. Margin of hydrotheca smooth 43 



42. .Margin of hydrotheca denticulate 44 



43. Hydrotheca broadly carnpanulate ; gonotheca with about 10 annulae 



C. integra 8 



43. Hydrotheca large, cylindrical, delicate: long slender pedicel with 

 1 distal and 2 or 3 proximal annulae only C. ritteri 2 



43. Hydrotheca very large, tubular, urceolate, with everted margin; 



hydranth with 20 tentacles C. regia 2 



44. Hydrotheca with longitudinal striations 45 



44. Hydrotheca unstriated 47 



45. Hydrotheca small, tubular; striations due to deep longitudinal 



flutings and continuous with 7-10 sharp teeth C. kincaidi 7 



45. Striations continuous with interdenticular spaces 46 



46. Hydrotheca deep, tapering to pedicel, margin with 10-12 square- 



topped teeth; gonotheca elongate, with numerous large annulae 



C. hincksi (p. 53) 



46. Hydrotheca large, delicate, depth to breadth as 3:2, sides parallel, 

 base hemispherical; 12-14 rounded teeth C. lineata' 



46. Hydrotheca large, deeply carnpanulate, urceolate, with short ped- 



icel; 10 low, blunt teeth; striations in distal quarter..C. speciosa 1 



47. Rim of hydrotheca usually everted, with 12-15 low teeth or crena- 



tions; gonotheca smooth, compressed, with small terminal 



aperture C. everta (p. 51) 



47. Hydrotheca deep, cylindrical, with 12 blunt marginal teeth; gono- 



thecae fusiform C. fusiformis (p. 52) 



47. Hydrotheca variable, margin often reduplicated, with 12-15 



rounded teeth ; gonotheca fusiform C. urceolata (p. 54) 



47. Hydrotheca small, tubular, margin often reduplicated, with 9 



moderate teeth , C. volubilis (p. 54) 



48. Hydrotheca deep, margin with 10 square-topped or bicuspid teeth; 



gonophores with tentacles but without radial canals 



G. clarki (p. 55) 



48. Hydrotheca deep, with 10-11 sharp teeth ; gonophores with radial 

 canals and tentacles G. gracilis 3 



48. Hydrotheca funnel-shaped, with smooth margin; gonophore with- 



out radial canals or tentacles G. inornata 2 



49. Medusae with 4 tentacles when liberated Clytia 50 



49. Medusae with 16 or more tentacles when liberated Obelia 51 



50. Hydrotheca carnpanulate, with even margin and usually thick 



walls; gonotheca irregularly ovate, with wide aperture .... 



C. caliculata" 



50. Hydrotheca usually with thick walls; margin slightly crenate; 

 gonotheca broadly ovate, compressed C. eompressa (p. 58) 



50. Hydrotheca with 13-15 marginal teeth; gonotheca with a single 



constriction in the middle C. johnstoni 



51. Margin of hydrotheca dentate or undulating 52 



51. Margin smooth 53 



52. A line running from each depression in the margin halfway to the 



base O. dubia 2 



52. Stem fascicled; margin of hydrotheca with bicuspid teeth 



O. gelatinosa 8 



52. Stem fascicled, branches sub-verticillate; margin of hydrotheca 



with shallow undulations O. longissima s 



