342 ME. HENEY B. BIGELOW— BISCATAN PLANKTOX : 



their figure, wliicli is of the superior nectophore only, leaves much to be desired, but, 

 as Leuekart long ago observed, the species which they studied was undoubtedlj'- a 

 Prayid ; while the presence of a globular swelling at the extremity of the somatocyst 

 points strongly to its identity with the P. cUphyes of Vogt and Kolliker, rather tlian 

 with any other species of the subfamily. Nor is tliere anything in the original figure or 

 description to forbid the union of the two. It is, of course, most desirable to identify 

 the older and usually very insufficient figures and descriptions of Siphonophores with 

 the species actually known to-day, and it seems that in the present case this can be done 

 safely. 



The name Praya diphyes was first used by Lesson (1843) [the quotation by Vogt of 

 Blainville, 1834, for this name is an error] for the Diphyes prayensis of Quoy and 

 Gaimard, a species founded for a single detached nectophore. It Avas regarded by Vogt 

 as identical with the species he studied. But Quoy and Gaimard's figures (1834, pi. 5. 

 figs. 37, 38), so far as they go, agree better with P. cymbifnrmis. 



Occurrences : 250 to fathoms. 36 h, 36 i. 6 superior, 5 inferior nectophores. 

 300 to fathoms. 36 k. 6 „ 2 „ 



350 to fathoms. 36 1. 3 „ 3 



1250 to fathoms. 27 a. 1 



300 to 200 fathoms. 21<?, 26/. 2 „ 1 „ 



The superior nectophores range from 12 mm. to 21 mm. in length, and from 9 mm. to 

 17 mm. in breadth ; the inferior ones from 12 mm. to 22 mm. and from 7 to 15 mm. 

 respectively. 



When the collection reached my hands all the nectophores here listed were separate. 

 The older [inferior] and younger [superior] ones, however, are not only easily identified, 

 but from their sizes can often be associated with each other in pairs. In all the 

 specimens the greater part of the corni and appendages are broken ofi', but in one I was 

 able to find a well-jireserved special nectophore, in addition to many crowded gonophores, 

 siphons, tentacles, and the remnants of bracts. This discovery, of course, makes its 

 generic identification certain. 



The specimens are identified with R.plicata (rather than with R. medusa, Metschnikoff 

 1870= P. diphyes, Graeffe, 1860= P. rosea, Chun, 1885), because of the absence of 

 tentacular rudiments on the margin of the special nectoi^hore. Diagnostic also is 

 the comparatively small size of the nectosac, the short oval form of the nectophores, and 

 the presence of well-marked hydroecial furrows. In P. medusa, as clearly shown in the 

 figures by Metschnikoff (1870) and Bedot (1895), the chief nectophores are triangular, 

 the nectosacs relatively very large. A single colony of P. medusa, from the Pacific, 

 which I have examined, agrees with these figures, in the almost total suppression of 

 the hydrcEcium. The two nectophores are merely slightly concave ventrally and 

 closely apposed to each other. 



Comparison between the Biscayan specimens and excellently preserved material 

 of Pray a cymbiformis, Delle Chiaje ( = P- maxima, Gegenbaur), from both the Mediter- 

 ranean and the Pacific, shows differences in the forms of the younger (superior) of the 

 two chief nectophores, sufficient for identification, even if the stem be lacking. 



