22 University of California Publications. [zoology. 



53. Stem fascicled - 54 



53. Stem not fascicled 55 



54. Stems interwoven, often of great length (18 in.) ; hydrotheea 



funnel-shaped O. borealis" 



54. Stem and larger branches fascicled; branching profuse; hydrothe- 

 eae broadly campanulate, slightly everted 0. plicata* 



54. Stem and branches long, flexuous; perisarc delicate; length of 



hydrotheea. 5 m. ; breadth, 4 m.; tentacles 22-24 O.-fragilis 3 



55. Hydrotheea polygonal at margin 56 



55. Single geniculate stem; pedicels usually on shoulders reinforced 



by a thickening of the perisarc; medusa with 24 tentacles .. 



O. geniculata (p. 58) 



55. Dimensions of hydrotheea: length, .30 m., .32 m.; breadth, .34 in., 



.19 m. ; hydranth with 28 tentacles O. gracilis 3 



55. Colony much branched; diaphragm in hydrotheea single, with 



down-turned edges; hydranth with 24 tentacles; medusa with 24 



tentacles, 6-8 medusae being borne at one time.-- 0. griffinr 1 



55. Colony 25 mm. high, branches relatively long, alternate: margin of 



hydrotheea slightly everted, diaphragm a simple shelf; medusa 

 with 28 tentacles O. surcuhtiis 



56. Branches sub-vertieillate ; medusa with 16 tentacles at liberation.. 



O. eommissuralis (p. 56) . 



56. Branching irregular; medusa with 20-24 tentacles at liberation ... 



O. diehotoma (p. 57) 



57. Hydrotheea larger below, narrowing slightly above, then expand- 



ing to the orifice H. pocillum s 



58. Branched, annulated throughout; long slender converging teeth 



form operculum; free bell-shaped medusa.. ..Campanulina rugosa 2 



58. Unbranched, hydrotheea tubular, pedunculate, opercular pieces dis- 



tinct from hydrothecal teeth Calycella syringa" 



59. Stem short, sparely branched or not at all; hydrotheea .60-. 65 m. 



long, with 7 large teeth Thaumantias inconspieua 3 



60. Stem fascicled 61 



60. Stem not fascicled; hydranth curved, decumbent, attached for t 



its length Filellum serpens 8 



61. Hydrothecae free or partially immersed Lafoea 62 



61. Hydrothecae partially adnate to axial tube, completely inclosed 



by peripheral non-thecate tubes Grammaria 65 



62. Hydrothecae short or sessile 63 



62. Hydrothecae pedunculate 64 



63. Colony encrusting L. adhaerens" 



63. Colony erect, hydrothecae short, stout L. dumosa (p. 59) 



64. Hydrotheea long, slender, delicate, with slender twisted pedicel 



i its length L. graeillima (p. 60) 



64. Hydrotheea stouter; pedicel annulated, J-4 length of hydrotheea... 



L. frutieosa" 



65. Hydrothecae in 8-9 rows, spirally arranged G. immersa 2 



66. Hydrothecae in one row, several to an internode 



Hydrallmania group 67 



66. Hydrothecae in two rows 68 



66. Hydrothecae in three or more rows Selaginopsis group 91 



67. Distal end of hydrotheea not reaching beyond proximal third of 



next one above; 3-5 to an internode H. distans (p. 70) 



