NO. 1 FRASER: HYDROIDS 37 



eels that are annulated below the base of the hydrothecae and some- 

 times at the proximal end as well. Hydrothecae, in face view, almost 

 equilaterally triangular. Margin entire, without flare. 



Gonosome. — Gonangium large, 1.4 mm. long, growing directly 

 from the stem between the nodes ; smooth, elliptical or slightly obovate ; 

 opening small, terminal ; no collar. 



Distribution. — Santa Elena Bay, 8-12 fathoms. 



Obelia geniculata (Linn.) 



Sertularia geniculata LiNNAEUS^ Syst. Nat., 1767, p. 1312. 



Obelia geniculata HiNCKS^ Br. Hyd. Zoophytes, 1868, p. 149. 



Distribution. — Braithwaite Bay, 16-18 fathoms; Tagus Cove, low 

 tide; reef north of the entrance to Tagus Cove, low tide. 



Obelia hyalina Clarke 



Obelia hyalina Clarke, Bull. Mus. Comp. Zool., Harvard, 1879, 

 p. 241. 

 Fraser, Beaufort Hyd., 1912, p. 363. 



Distribution. — East of islands off Navidad Head, 25-35 fathoms; 

 Santa Maria Bay, 10 fathoms; Thurloe Point, low tide; South Bay, 

 Cerros Island, 10-15 fathoms. 



Obelia microtheca, new species 

 Plate 9, Fig. 40 



Trophosome. — Colony small, slender, reaching a height of 4 mm., 

 but usually much less. Hydrothecae quite regularly alternate, with a 

 tendency to geniculation. Pedicels 1-2 times as long as the hydrothecae. 

 Stem annulated above the origin of each pedicel ; pedicel annulated in 

 at least the distal half. Hydrothecae nearly equal in breadth and length ; 

 small, 0.2 mm. Margin entire. 



Gonosome. — Gonangium resembling that of O. dichotoma, arising 

 with a short pedicel from the axil of the hydrothecal pedicel, 0.5-0.6 

 mm. in total length; a definite collar much smaller than the distal por- 

 tion of the gonangium. 



Distribution. — Santa Elena Bay, 10 fathoms. 



