74 University of California Publications. [zoology. 



Antenella avalonia, sp. no v. 



PI. X. Figs. 92, 93, 94. 



Trophosome. Stems rooted by creeping stolon, unbranehed; longest 

 7 mm. high, with five hydrothecae. Each stem divided bv alternately 

 oblique and transverse nodes, which are always weak, into alternating 

 thecate and intermediate internodes. Hydrothecae as deep as broad, free 

 for half their length, with slightly everted circular margin. Mesial nemato- 

 phores borne on small processes of the stem. Intermediate internodes with 

 one or two nematophores, never three. 



Gonosome. Gonothecae broadly ovate, with short, slightly ringed pedun- 

 cles, borne in pairs on the thecate internodes, one on each side of the mesial 

 nematophore. Pair of nematophores at the base of each. 



Distribution. Avalon, CatalinaL, Cal. 



This species differs from Monostaechas quadridens McCrady 

 only in size, absence of hydroeladia and the occurrence of the 

 gonothecae in pairs. It is possible that the first two differences 

 may be due to immaturity; yet on no stem was there a remote sign 

 of a branch. On one stem 5 mm. long there were three pairs of 

 male gonothecae, decreasing in size distally, none quite mature, 

 though suggesting the maturity of the colony. 



The branching form is probably to lie derived from the 

 unbranehed form, the first branch arising from the base of the 

 proximal hydrotheca and remaining non-thecate in its proximal 

 portion; the second branch would arise at the base of the proxi- 

 mal hydrotheca of this first brauch, and possess a distal thecate 

 and proximal non-thecate region; the third branch would develop 

 in a similar way on the second, and so on. Two branches may 

 arise at the same point, producing a false dichotomy, as in .1/. 

 quadridens. 



Cat. No. 689a., University of California Collection. Type. 



Halicornaria, Busk. 



Trophosome. "Stem not fascicled, no posterior intrathecal ridge; an 

 anterior intrathecal ridge usually present ; hydroeladia not branched; hydro- 

 cladial internodes without septal ridges. 



Gonosome. "Gonangia borne on the stem or on the bases of the hydro- 

 eladia not taking the place of hydrothecae, and not protected by eorbulae or 

 phylactocarps of any description." (Nutting, '00.) 



