38 Bulletin, Vanderbilt Marine Museum, Vol. IV 



Family: VELELLIDAE. 



Genus: VELELLA Lamarck. 

 Velella velella (Linne). 



Type : Linne 's type came from the Mediterranean Sea ; present de- 

 pository unknown. 



Distribution: In American waters known from the "West Indian 

 region and in the Gulf Stream as far north occasionally as Nantucket, 

 Rhode Island; in the tropic Atlantic eastward to the Azores; also in 

 the Mediterranean Sea. 



Material examined: Two specimens, 10 miles S. by E. of Monaco 

 Harbor, April 19, 1927. One specimen, taken 4^/2 miles off Monaco, 

 March 20, 1927. 



Color: See Prof. Agassiz's color plate, made from Florida speci- 

 mens, Mem. Mus. Comp. Zool., vol. VIII, pi. 1, 1881-83. 



The mantle is a metallic bluish green with a deep cobalt blue margin 

 surrounding the float and a similar band forming nearly an ellipse 

 across the float. Between these bands of color the float passes from 

 yellowish green to the dark blue marginal bands. The entire mantle 

 is dotted with patches of brownish liver cells. The extreme outer 

 margin of the mantle is fringed with a light cobalt blue band, through 

 which the lower side of the tentacles of the float show. The mantle 

 where it covers the central part of the float is light greenish blue with 

 metallic lustre and with few liver cells, diminishing in abundance 

 toward the base of the keel. The greenish color forms concentric lines 

 parallel with the chambers of the float, crossed by triangular radiating 

 rays extending from the fixed mantle margin towards the base of the 

 keel, dividing the float into irregular alternating sections of light 

 colored spaces. The keel is delicate steel color, with a thickened mar- 

 gin of the mantle extending around it; there are dark violet patches 

 of liver cells in the mantle margin. 



Life history: Extensive critical work has been done upon this 

 species (see bibliography). In 1859 T. H. Huxley reported the 

 larval forms. 



Technical description : Consult Agassiz, Mem. Mus. Comp. Zool., 

 vol. 8, for description of the West Indian form, and Krohn, Archiv. f . 

 Naturg., 1848, I, p. 30, for that of the Mediterranean form. Agassiz 

 reviews the research done on the younger stages of Velella velella by 

 Kolliker, Gegenbaur, Vogt, Huxley, Stuart and other workers. 



