24 University of California Publications. [zoology. 



79. Aperture semilunar 84 



80. Hydrotheca abruptly narrowed distally, aperture round 81 



80. Hydrotheca not abruptly narrowed distally, aperture round or oval 83 



81. Hydrothecae sub-opposite to alternate; orifice of gonotheca large, 



round, with a number of teeth projecting downward 



Sertularia variabilis 1 



81. Hydrothecae alternate; gonotheca widest in middle, tapering to 



both ends, aperture small, terminal 82 



82. Gonotheca smooth Sertularia filieula (p. 68) 



82. Gonotheca with about five conspicuous longitudinal ridges 



Sertularia eostata 2 



83. Hydrotheca tubular, deeply immersed, with round aperture, 



opposite on branches ; gonotheca with three or five lodgitudinal 

 ridges Thuiaria turgida' 



83. Hydrothecae subalternate, deeply immersed, curving outward, oval 



aperture; stem and branches stout; gonotheca ovate; large ter- 

 minal aperture Thuiaria gigantea 1 



84. Branches spirally arranged, hydrothecae sub-opposite to alternate, 



distal end of alternate reaching beyond base of next ; gonotheca 

 bimucronate Sertularia thuiaroides 1 



84. Branches pinnate, distal end of alternating hydrotheca barely 



reaching base of next Sertularia traski (p. 69) 



85. Hydrothecae opposite on branches, curved strongly outward 



Sertularia similis 1 



85. Hydrothecae alternate on branches 86 



86. Hydrothecae on main stem 87 



86. No hydrothecae on main stem; even number of alternating 



branches to an internode, hydrothecae deeply immersed 



Sertularia cupressoides' 



87. Gonotheca with two horns or spines 88 



87. Gonotheca without horns or spines 90 



88. Hydrotheca never completely immersed 89 



88. Hydrotheca completely immersed in median portion of branches 



only; hydrocaulus largest distally; gonotheca with two truncate 

 spines Thuiaria robusta 1 



88. Hydrotheca always completely immersed: aperture toward stem: 



gonothecae very long, bieornuate, in single row on upper side of 

 branches Thuiaria plumosa 1 



89. Aperture well defined ; gonothecae constantly bimucronate 



Sertularia argentea (p. 67) 



89. Aperture less clearly defined; gonothecae only occasionally bimu- 



cronate Sertularia fabricii 3 



90. Gonotheca with bottle-shaped distal end, small round aperture; 



hydrotheca with two prominent teeth; stems densely clustered ... 

 Sertularia greenei (p. 69) 



90. Gonotheca ovate, round aperture; colony one-half inch high, stem 



flexuous, hydrotheca free for distal half Sertularia tenera 7 



91. Hydrothecae tubular, almost completely immersed 



Selaginopsis cylindrica 1 



91. Hydrothecae immersed for half their length, narrowing distally 



Selaginopsis mirabilis 1 



92. Nematophores movable 93 



92. Nematophores fixed 101 



93. Hydrocladia borne on erect stems Plumularia 94 



