44 CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 
radial canals arise directly from the funnel. The 4 meridional subventral 
vessels are very long and extend around the aboral side of the narrow 
edge of the body. The 4 meridional subtentacular canals each give 
rise to a short tract of cilia and then bend downward and outward along 
the middle of the sides of the animal and join with the meridional sub- 
ventral canals and the oral forks of the paragastric canals at the extremi- 
ties of the long sides of the animal. Each of the 2 median tentacles arises 
from a deep sheath. The sexual products are developed only in the long 
subventral canals. The larva passes through a Mertensia-like condition 
in which the tentacular axis is longer than the stomodeal axis. 
Species of Cestum are found in all the warmer oceans. The type 
species is Cestum veneris Lesueur, of the Mediterranean and tropical 
Atlantic. ‘“Cestum amphitritis” of Mertens, 1833, appears to be the 
same species from the tropical Pacific. 
Cestum veneris Lesueur. (Figs. 60 and 61, plate 12.) 
Cestum veneris, LESUEUR, 1813, Nouv. Bulletin des Sciences de la Sociét. Phil., 
tome 3, p. 281, planche 5, fig. 1— Lresson, 1836, Annales des Sci. Nat., sér. 2, 
tome 5, p. 245.—Fot, 1869, Beitrag Anat. Entwick. Rippenquallen, Berlin, 
p. 8, Tafin. 2-4. 
‘Cestus veneris, CHUN, 1880, Ctenophoren des Golfes von Neapel, pp. 53, 135, 152, 
181, 301, Taf. 11-13 (full list of literature) —ALLMAN, 1881, Journal Linnean 
Soc., London, vol. 16, p. 106.—CuHuNn, 1898, Ctenophoren des Plankton-Exped., 
p. 20.—GRAEFFE, 1884, Arbeit. Zool. Inst. Wien, Bd. 5, p. 362.—-WaAGNER, 
N., 1885, Die Wirbellosen des Weissen Meeres, p. 54.—R6MER, 1903, Fauna 
Arctica, Ctenophoren, Bd. 3, p. 85.—VANHOFFEN 1906, Nordisches-Plankton, 
Ctenophoren, 11, p. 6, Fign. 14, 15.—Samassa, 1892, Archiv fiir mikroskop. 
Anatomie, Bd. 40, pe. 169, 218 (histology)—MoseEr, 1908, Abhandl. Akad. 
Mitinchen, Suppl. Bd. 1, Abhandl. 4, p. 12. 
Cestum amphitrites, MERTENS, 1833, Mém. Acad. Sci. St. Pétersbourg, Sci. Math. 
Phys. et Nat., sér. 6, tome 2, E 492, Taf. 1 (tropical Pacific). 
‘Cestus pectenalis, BiGELoW, 1904, Bull. Museum Comp. Zool. at Harvard College, 
vol. 39, p. 267, plate 8, fig. 30 (Indian Ocean). 
The animal is flat and ribbon-shaped, being about 80 mm. high and 
sometimes over 1,500 mm. wide, although specimens over 800 mm. in 
width are not common. The body is strongly compressed in the ten- 
tacular diameter. The apical sense-organ is a simple capsule containing 
a cluster of concretions, and is slightly depressed beneath the general 
level of the body surface. The long, narrow aboral side of the animal 
is arched and bears small, wart-like protuberances. The ventral, ten- 
tacle-bearing edge is much narrower than the aboral edge, and the sides 
bulge slightly outward so that the animal is widest midway between 
mouth and apex. The subtentacular rows of combs are represented by 
4 short tracts close to the sides of the sense-organ. Beyond these there 
is a short, free interval, and then commence the 4 long subventral rows 
of combs which extend along the sides of the arched aboral edge of the 
animal. Simple tentacles, closely set in a double row, extend along 
the sides of the oral edge of the animal, following the courses of the oral 
branches of the paragastric canals. 
The stomodzum is cruciform in cross-section, being slightly out- 
folded in the tentacular (funnel) axis, although wider in the sagittal 
axis. The funnel is about one-third to one-fourth as long as the height 
of the animal, becoming relatively shorter as the animal increases in 
size. The 4 slender, interradial canals arise from the funnel, as do also, 
