164 EXPEDITION OF THE "ALBATROSS," 1899-1900. 



Aglaisma quincunx Mater. 



Aglaisma quincunx Mater, 1900; Bull. Mus. Comp. Zobl., Vol. XXXVII, p. 78. (Atlantic 

 form.) 



Plate 10, fig. 45. 



A large number of specimens of this Siphonophore were obtained 

 throughout the Tropical regions of the Pacific. A comparison of the 

 Figures here given with those of the Atlantic form by Chun, 1897, and 

 Mayer, 1900, will serve to show the close relationship which exists between 

 the Pacific and the Atlantic representatives of this Siphonophore. It will 

 be noticed that in Figure 45 a saw-toothed projection extends down the 

 open groove of the inferior nectophore, and that this is absent in the Fig- 

 ures of the Atlantic form given by Chun and Mayer. This peculiarity is, 

 however, not seen in all individuals, and seems to occur cp:iite as commonly 

 in the Atlantic as in the Pacific specimens, and it cannot, therefore, be used 

 as a basis of distinction between them. The Pacific and Atlantic specimens 

 are, moreover, of the same size, being about 7-9 mm. in length for the 

 Diphyes, and 4-5 mm. for the Aglaisma generation. The only fairly con- 

 stant difference appears to be that in the Atlantic specimens the terminal 

 nematocyst batteries of the tentacles are usually orange or yellow in color, 

 whereas in the Pacific forms they are generally colorless. This distinction 

 is not invariable, however, for some Pacific specimens are found in which 

 they are slightly yellow, while other specimens from the Atlantic have them 

 colorless. 1 We therefore conclude that there can be, at most, but a varietal 

 difference between the Atlantic and Pacific forms of this Siphonophore, and 

 venture to assert that they belong to the same species. 



(300 f — S) n ; Station 25; September 14, 1899 ; Marquesas Islands. 

 (300f — S) d ; " 30; " 18, " S. Lat. 10° 29', W. Long. 141° 52'. 



(300 f — S) rf , S d ; ■ October 28, " off Marokau Island, Taumotus. 



S*; Station 173; November 4, " S. Lat. 18° 55', W. Long. 146° 32'. 



S"; December " Suva Harbor, Fiji Islands. 



S''; " 25, " Lagoon of Funafuti, Ellice Islands. 



1 We had also found this species in Fiji in 1897-98. See Bull. Mus. Comp. Zool., 1899, Vol. 

 XXXIL, No. 9, p. 180. 



