vol.i.] Torrey. — Hydroida of the Pacific Coast. 55 



Distribution. San Pedro and Tomales Bay, Cal. Bare I., 

 near Vancouver, B. C. (Hartlaub). Oulf of St. Lawrence, 20-30 

 fathoms, (Packard). Massachusetts (Agassiz) . "Off Reikiavik, 

 Iceland, in 100 fathoms, amongst icebergs, on Sertularia" 

 (Hincks). Norway (Sars). Mingan Is. (Hincks). 



Dredged near San Pedro, Cal., from a sandy bottom covered 

 with small stones and some kelp roots, in 9 fathoms. A single 

 gonotheca, lost before it could be drawn, was much compressed. 

 The margin of the hydrotheca is furnished with nine teeth and is 

 frequently reduplicated. The colonies from Tomales Bay grew 

 between the tides. 



Gonothyraea clarki, nom. nov. 



Gonothyraea hyalina, a. V. Clark, Proe. Phil. Ac, 1776, XXVIII, p. 

 215. 



Distribution. Oakland, Cal. Alaska, 13-30 fathoms (Clark). 

 Shetland (Hincks). 



The form from Oakland Harbor agrees in all respects with 

 Clark's description, save that the extracapsular medusoids are 

 more nearly spherical than those of Clark's material. Male and 

 female medusoids are of the same size and shape, the tentacles of 

 the female being possibly a little longer. A feature which dis- 

 tinguishes this species from O. loreni is the absence of radial 

 canals, though an endodermal lamella is present. The skeletal 

 characters of the two are indistinguishable (Nutting) . Hincks's 

 G. hyalina was in all probability a form of G. loveni. 



The ectoderm of the manubrium is very thin and may lie 

 close to the subumbrella ectoderm so that the bell, lacking mes- 

 enchyme entirely, often appears in section to be composed of four 

 extremely attenuated closely applied cell layers. The endoderm 

 of the manubrium is a conspicuous layer of darkly staining col- 

 umnar cells, showing signs of glandular activity and without 

 doubt furnishing with yolk the ova which are pressed against it. 



I have never seen a medusoid leave the gonotheca and do not 

 know whether it actively aids itself or not. Certainly it does not 

 move, so far as I have observed, after leaving the gonotheca. 

 The blastostyle thins out as the medusoids leave, as though 

 under a tension. But this tension could hardly be exerted by 



