NO. 5 FRASER : HYDROIDS 277 



Plumularia diaphana (Heller) 

 Anisocalyx diaphanus Heller, Adriatic Hyd., 1868, p. 42. 

 Plumularia alternata Nutting, Amer. Hyd., I, 1900, p. 62. 



Fraser, Hancock Hyd., 1, 1938, p. 62. 



Fraser, ibid., 3, 1938, p. 135. 

 Plumularia diaphana Fraser, Atlantic Hyd., 1944, p. 342. 



Distribution. — Sulphur Bay, Clarion Island, 12 fathoms; off Isabel 

 Island, Mexico, 10-15 fathoms; off Secas Islands, Panama, 12 fathoms. 



Plumularia exilis, new species 

 Plate 38, Fig. 43 



Trophosome. — Colonies are loosely clustered, growing to a height of 

 3.5-4.0 cm; the stem is unbranched, slightly sinuous, very slender, di- 

 vided into long internodes by well marked nodes. The hydrocladia are 

 regularly alternate; as the internode is long, the hydrocladia are distant 

 from one another ; supported by a cauline process, almost at the distal end 

 of the internode; the angle with the stem is 45-50°. The hydrocladium is 

 very slender, much similar in diameter to that of P. tenuissima Fraser. 

 The nodes are strongly marked, usually flanked by an evident, internodal 

 septum on each side. The first internode is short, athecate, the second is 

 long, with the hydrotheca about two-thirds of the way up; the third 

 internode is athecate, long, but not so long as the thecate internode ; after 

 the third, thecate and athecate internodes, like the second and third, al- 

 ternate. The hydrotheca is correspondingly small. There is no nemato- 

 phore on the short, proximal internode ; on the second, there are 2 mesial 

 nematophores proximal to the hydrotheca, and the 2 supracalycine nemat- 

 ophores ; on the athecate internode, there are 2 mesial nematophores ; on 

 the stem, there is a nematophore in the axil of the process, as well as 3 or 

 4 nematophores on each internode on the side opposite the process. 



Gonosome. — The gonangia are numerous, arising from the main stem 

 near the axil of the hydrocladial process, or from any part of the hydro- 

 cladial process, or from any part of the hydrocladium; they are long, up 

 to 1.25 mm, and very slender; they may taper to a small opening at the 

 distal end, or they may be truncate. 



Distribution. — Station 618-37, San Jaime Bank, off Cape San Lucas, 

 Lower Calif., 75 fathoms; 6^ miles north of Anacapa Island, 125-135 

 fathoms; east of Anacapa Island, 50 fathoms; NE of Anacapa Island, 45 

 fathoms; 10% miles west of Point Dume, Calif., 47-48 fathoms; east of 

 Long Point, Santa Catalina Island, 45-50 fathoms ; 2.8 miles WNW of 



