146 THE VOYAGE OF H.M.S. CHALLENGER. 



The genus Praya, and the following genus Lilyopsis, compose together the sub- 

 family Prayidse, differing from the other Diphyidae (Diphyopsida? and Abylidse) mainly 

 in the rounded, edgeless exumbrella of the nectophores, which consist of a particularly 

 soft jelly-substance, much softer than in the latter. The two nectophores are of similar 

 form and nearly equal size, one opposed to the other, and not the first before the second 

 (as in the Diphyopsidse and Abylidse). The mitriform or reniform nectophores have a 

 longitudinal furrow on their ventral side, and the two hemicylindrical furrows are so 

 applied one to another as to form a hydrcecial tube, in which the upper part of the 

 siphosome can be retracted. The bracts are navicular or reniform, provided with four 

 irregular radial canals. 



The best known type of the genus Praya is the large Mediterranean form described 

 by Gegenbaur as Praya maxima (7, Taf. xvii. figs. 1-4). Perhaps different from this 

 species is another Mediterranean form, which also inhabits the North Atlantic, Praya 

 cymbiformis, delle Chiaje (18), very accurately described by Leuckart (5 and 8). A third 

 species, differing from the two former in the form of the nectophores and bracts and their 

 canals, is the tropical Atlantic Praya galea, which I observed living in the Canary 

 Island Lanzerote, in February 1867. Scattered bracts of it are found in a bottle in the 

 Challenger collection from Station 352. 



Praya galea, n. sp. (Pis. XXXL, XXXII. ). 



Praya galea, Haeckel, System der Siphonophoren, 1 888, p. 35. 



Habitat. — Tropical and Subtropical Atlantic, Station 352 ; April 13, 1876 ; lat. 

 10° 55' N., long. 17° 46' W. Surface. 



Canary Islands, Lanzerote, February 1867 (Haeckel). 



Nectophores (PI. XXXL figs. 1-7, natural size; fig. 1, lateral view; fig. 2, dorsal 

 view ; fig. 3, apical view of the two united, fig. 4, of the two separated nectophores ; 

 fig. 5, first (smaller) nectophore from the left side ; fig. 6, second (larger) nectophore 

 from the right side ; fig. 7, the same from the ventral side). The two large nectophores 

 or nectocalyces, which are the powerful locomotive organs of the long chain-like body, 

 are both of similar kidney-shaped form, but of different sizes. The first, apical or 

 proximal nectophore is somewhat smaller than the second, basal or distal swimming bell ; 

 both possess a deep longitudinal groove on their ventral side, and are so opposite one to 

 another at the top of the stem, that the larger distal bell is placed more below and 

 embraces the smaller proximal bell by means of its two lateral ventral wings (figs. 3, 4). 

 The smaller nectophore was in the largest specimen, which I examined living in the 

 Canary Islands, 40 mm. long and 25 mm. broad ; the larger (second) nectophore 50 mm. 

 long and 35 mm. broad. Another specimen had only two-thirds of this size. 



