7(1 BULLETIN OF THE BUREAU OF FISHERIES. 



PELAGIA Peron & Lesueur (1809). 



Pelagia cyanella Peron & Lesueur. PI. VII, tig. 1. 



I; lagia cyaneUa Peron .v Lesueur, Tableau des Meduses, etc , 1809, p. 349. Eschscholtz, System dor Acalephen, 1829, p. 75. 

 L. Agnssiz, Contributions Natural History United States, Vol. IV, 1862, p. 164. A. Agassiz, North American 

 Acalephse, 1865, p. IT Haeekel, System dor Medusen, 1879, p. 507. 



I'mbrella somewhat dome-shaped, or subhemispherical; marginal lobes 16, with 8 rhopalia and 

 8 tentacles symmetrically disposed in the sinuses of the marginal lobes. Gonads 8, forming conspicu- 

 ous pouch-like masses within the gastric pouches of the tentacular radii. Manubrium large and pen- 

 dulous, with 4 variously frilled oral anus approximately as long as the tentacles. 



( 'olors. — l>isk translucent bluish, sprinkled with reddish brown dots over the exumbrellar surface, 

 though more numerous near the margins and along certain radial areas, and forming crescent-like 

 loops on the marginal lappets; manubrium similarly mottled on the outer edges of the arms, inner 

 edges and frills delicate flesh colored; tentacles dull madder red to brownish red. Gonads pale pur- 

 plish. Like Dactylometra, the color of Pelagia is more or less variable in different specimens. 



This is a rare medusa in this region, only two specimens having been taken recently, both south- 

 ward from Marthas Vineyard in the region of the Gulf Stream. Distribution chiefly pelagic. 



According to Agassi/, (above citation) the development of this medusa is direct, skipping the polyp 

 and strobila stages and transforming directly from the planula to the ephyra and medusa. 



CTENOPHORA." 



While there continues to be widespread uncertainty as to the exact systematic 

 relations of the ctenophores. there can be little doubt as to their more or less general 

 relationship with the coelenterate phylum, hence their inclusion in the present 

 synopsis. 



In general they may be considered free-swimming medusoid coelenterates of 

 pelagic habit, wholly destitute of the polyp phase of the preceding classes. More- 

 over, there is lacking any tendency to a colonial habit, so characteristic of the pelagic 

 siphonophores. budding or proliferous asexual reproduction being unknown among 

 them. Ciliary locomotion, so characteristic a larval condition in the former group, 

 continues throughout the entire life of ctenophores, though the cilia become greatly 

 modified, appearing as plates occupying definite meridional areas over the body. 

 Tentacles may be entirely lacking, and when present are but two in number and 

 located on opposite sides of the body, in perradial planes, and capable of contraction 

 within lateral pockets. Again, nematocysts, so distinctive a feature of the classes 

 previously described, are wholly lacking here, though certain cells of the etoderm of 

 the tentacles, known as adhesive cells, may possibly be regarded as homologous with 

 them, and may aid in taking prey. 



The gastrovascular system is well developed. The stomodeum, or so-called 

 stomach, is usually large and opens above into the principal cavity of the canal sys- 

 tem, the so-called funnel, or infundibulum. This divides into 8 terminal branches 

 occupying adradial positions at their peripheral extremities. The stomach and funnel 

 planes of the body are at right angles, and comprise the perradial planes known, 

 respectively, as stomach and funnel planes. There are no signs of gastral filaments. 



The muscular system is but slightly developed as such, though there are numer- 

 ous muscular fibers intricately distributed through the mesogkea. Many of these 

 libers tire curiously branched and poly nucleated. 



"This account presents merely the briefest synopsis of the species found within the region. 



