CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 43 
Order CESTIDA: Gegenbaur, 1856. 
Callianiride, EscuscuHoitz, 1829, Syst. der Acal., p. 21. 
Cestoide@, Lesson, 1843, Hist. Zooph. Acal., p. 68. 
Cestide, GEGENBAUR, 1856, Archiv fiir Naturgesch., Jahrg. 22, p. 196. 
Taeniate, Acassiz, L., 1860; Cont. Nat. Hist. U.S., vol. 3, p. 292. 
Cestide, Fou, 1869, Beitrag Entwick. einigen Rippenquallen, p. 6. 
Cestide, CHUN, 1880, Ctenophoren des Golfes von Neapel, p. 300.—VANHOFFEN, 
1906, Nordisches Plankton, Ctenophoren, x1, p. 6. 
CHARACTERS OF THE ORDER. 
Ribbon-shaped ctenophore in which the tentacular axis is mark 
edly compressed and the lobular axis correspondingly extended. The 4 
subtentacular rows of combs are rudimentary and the 4 subventral rows 
greatly extended. The axial tentacles have basal-sheaths. 
Thus in the Cestide we find an extraordinary development of the 
lateral compression seen in lesser degree in the Lobatze. The funnel- 
axis is thus reduced and the stomodzal axis greatly extended. This 
causes the subtentacular rows of combs to be rudimentary while the sub- 
ventral rows are correspondingly lengthened. The sheaths of the median 
tentacles recall the conditions seen in the Cydippide, and indeed the 
larve of the Cestidz when hatched from the eggs are Mertensia-like in 
appearance with the tentacular axis longer than the sagittal, this being 
the reverse of the condition which pertains in the adult. 
There are two genera, Cestum and Folia. In Cestwm the narrow, 
aboral edge of the animal is arched and the 4 subtentacular meridional 
canals extend upward from their points of origin and are provided each 
with a very short tract of cilia. They then bend downwards and finally 
outwards along the middle of the sides to the ends of the body, where 
they join the 4 meridional subventral canals. In the genus Folia the 
aboral narrow edge is flat and the 4 subtentacular meridional canals 
do not arch upward, but extend straight outward to the ends af the sides 
of the body. 
The oral branches of each paragastric canal fuse with the meridional 
vessels of their own side only, and thus the peripheral canal-system of 
each broad side of the body is separated from that of the other side; 
there being no circum-oral canal such as is seen in the Lobate. 
Species of Cestum are found in all of the warm oceans. Folia is 
represented by fF. parallela of the Mediterranean and tropical Atlantic. 
Genus CESTUM Lesueur, 1813. 
Cestum, LESUEUR, 1813, Nouv. Bull. des Sci., tome 3, p. 281.— EscHscHOLTzZ, 1829, 
Syst. der Akalephen, p. 23.—MERTENS, 1833, Mém. Acad. Sci. St. Péters- 
bourg, sér. 6, tome 2, p. 492.—MiLNE-Epwarps, 1857, Annal. des Sci, Natur- 
elles, Zool., sér. 4, tome 7, p. 291.—FoL, 1869, Anatomie und Entwick. der 
Rippenquallen, p. 8—BIcELow, 1904, Bull. Museum Comp. Zool. at Harvard 
College, vol. 39, p. 267. 
Cestus, CHUN, 1880, Ctenophoren des Golfes von Neapel, p. 301.—VANHOFFEN, 
1906, Nordisches Plankton, Ctenophoren, x1, p. 6. 
GENERIC CHARACTERS. 
Cestide in which the great extension of the sides in the stomodzal 
axis and the marked compression of the body in the tentacular axis 
cause the animal to assume the shape of a long, flat ribbon. The 4 inter- 
