184 THE MEDUSAE. 



Purena hrownei has a very wide range over the Pacific and Indian 

 oceans, a distribution suggesting that it reproduces by budding; but this 

 process has not yet been observed. 



Ectopleura L. Agassiz, 1862. 



Codonidae with either two or four perradial tentacles ; tentacles with 

 nematocyst batteries on the outer face only ; manubrium short ; exumbrella 

 with eight radial nematocyst ribs. 



Four species of Ectopleura have been described : — E. dnmortuYan Bene- 

 den ('44), from the European coast, E. ochracea A. Agassiz ('62), from the 

 Atlantic coast of North America, E. minerva Mayer (: 00''), from the Tortugas, 

 and E. padfica Thornely (: 00), from New Britain, the latter known from 

 the hydroid only. 



E. minerva is sufficiently well characterized by having only two tentacles. 

 E. ochracea and E. dumortii are so closely allied that it is hard to find any good 

 characters to separate them ; indeed Dr. A. G. Mayer assures me that he was 

 unable to distinguish specimens of E. dumortii taken off Cornwall from 

 E. ochracea from New England. 



The present collection contains a considerable series of the genus which I 

 have compared with numerous specimens of E. ochracea, the result being that I 

 am unable to find any characters distinguishing the two except such as may 

 depend on state of contraction or on differences in preservation. I therefore 

 refer the Pacific series to E. ochracea. 



Ectopleura ochracea A. Agassiz. 



Ectopleura ochracea A. Agassiz, '62, p. 343; '65, p. 191, figs. 320-32S ; Hargitt, :05'', p. 32, 

 pi. 2, fig. 1. 



Plate 6, Fig. B; Plate 38, Figs. 12, 13. 



Acapulco Harbor ; surface ; many specimens. 



The largest specimen measures 1 mm. in height by about 1 mm. in 

 diameter. 



The bell is high ; the gelatinous substa.nce is thick at the apex but it 

 does not form a distinct apical projection. It is possible, as Hartlaub (: 07) 

 suggests, that the form of the bell may prove a good distinction between 

 this species and E. dumortii, in which it is rounded, not thickened, aborally. 

 In all the specimens there is a well-developed apical canal. The tentacles 

 of E. ochracea are described (A. Agassiz, '65, p. 191) as having the nettle 



