NO. 5 FRASER : HYDROIDS 227 



Ophiodissa expansa, new species 

 Plate 25, Fig. 12 



Trophosome. — Colonies, growing in loose clusters, reach a height of 

 18 mm; the main stem, fascicled proximally, gives off a very few stout 

 branches, each of which resembles the simple portion of the stem. The 

 simple stem or branch is divided into internodes, varying somewhat in 

 length, by slightly oblique nodes, not very distinct. The hydrophores are 

 somewhat irregularly alternate, in some places almost subopposite, those 

 on the two sides not quite in the same plane. In every case the pedicels are 

 definite but vary much in length, sometimes corrugated slightly; the 

 hydrophores expand to the margin so that the aperture may be twice the 

 diameter of the supporting pedicel. The nematophores are large, tubular, 

 sometimes curved slightly, placed either on the cauline internode or on 

 the pedicel of the hydrophore. 



Gonosome. — The gonangium, 1.32 x 0.5 mm, arises from the fasci- 

 cled portion of the stem, projecting at right angles to it; it resembles 

 some of the Sertularella gonangia, e.g., those of S. tricuspidata (Alder). 

 It is elongated oval, with a short pedicel ; very strongly crested rugosities 

 appear throughout the whole length ; the aperture is large, terminal. 



Dv;tribution. — Station 1232-41, 5 miles — 152° from San Pedro 

 breakwater, 17-19 fathoms; 2 miles NW of buoy, Cortes Bank, 42-45 

 fathoms. 



Ophiodissa laxa Fraser 

 Ophiodissa laxa Fraser, Hancock Hyd., 1, 1938, p. 45. 

 Fraser, ibid., 3, 1938, p. 133. 

 Distribution. — North of Clarion Island, 35-36 fathoms. 



Family Hebellidae 

 Genus HEBELLA 

 Hebella calcarata (A. Agassiz) 

 Lafoea calcarata A. Agassiz, N. A. Acalephae, 1865, p. 122. 

 Hebella calcarata Fraser, Hancock Hyd., 1, 1938, p. 46. 

 Fraser, iZ^r^., 2, 1938, p. 110. 

 Distribution. — Dewey Channel, opposite San Eugenio Point, Lower 

 Calif., 21-24 fathoms; north of Clarion Island, 35-36 fathoms; inside 

 Georges Island, Gulf of California, 12-13 fathoms; south of Isla Partida, 

 20 fathoms; off White Rock, Isla Partida, 45 fathoms; south of White 

 Friars Islands, Mexico, 25 fathoms. 



