6 CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 
lobe. There are numerous, simple tentacles which extend along the 
wide sides of the mouth, and in the middle of each line there is usually 
a principal tentacle, which is commonly feathered and arises from a large 
projecting basal-bulb without a sheath. In Ocyropsis, however, there are 
neither tentacles nor tentacular canals. The subventral rows of combs are 
longer than the subtentacular. The larve pee through a stage in which 
they resemble the Cydippide, from which the Lobate are evidently 
descended. In the larva the tentacular axis is wider than the stomodzal 
axis, as in Cydippide, whereas the reverse is the case in the adult Lobate. 
IV. Cest1p&@: The lateral compression seen in the Lobate is greatly accentuated 
in this order, so that the body is flat and ribbon-like, the long side being 
in the stomodzal axis and the compression being in the funnel-axis. 
There is no ring-canal around the mouth, but the subventral and sub- 
tentacular vessels unite with the oral forks of the paragastric canals 
and the canal-systems of the two sides are separated, uniting only at the 
funnel. There is a row of tentacles along the oral forks of the paragastric 
vessels. The 2 median tentacles are the largest and are set within basal 
sheaths. The Cestide are closely related to Lobatez, and their larve pass. 
through a cydippe-stage as do the larvee of the Lobate. 
V. Breroip#: Lateral compression as in the Lobate and Cestide, the compression 
of the funnel-axis being generally more marked than in the Lobate, but not 
so pronounced as in the Cestide. Canal-system as in the Cestide, with the 
added feature that the meridional canals and the oral forks of the para- 
gastric canals give off side branches which may anastomose and form 
a network connecting some or all of the vessels, in some species forming 
acircumoral canal-system. The axial funnel-canal is absent and is replaced 
by two side branches which extend upward from the funnel to the excretory 
pores. There are no tentacles even in the larva, which in other respects. 
resembles the Cydippide. The stomodeum is very wide in the sagittal 
plane and constitutes a great sac, so that the funnel is very short. 
VI. PLatycTenipa: Creeping or sessile, degenerate ctenophores, with the oral- 
aboral axis much shortened, so that the oral and aboral sides of the 
animal are flat and expanded. With 2 tentacles, which in some forms. 
may be withdrawn within sheaths. The apical sense-organ may be present, 
but in some forms the combs of cilia are absent. There are 3 genera, 
Tjalfiella Mortensen, Coeloplana Kowalevsky and Ctenoplana Korotneff. 
The species occur in the Red Sea, Malay Region, Japan, and Greenland, 
and the most recent descriptions are by Willey, 1897, Quarterly Journal 
Microscop. Sci., vol. 39, p. 323; Abbott, 1902, Annot. Zool. Japonensis, vol. 
4, Pp. 103; and Mortensen, 1910, Vid. Meddel. Foren. Kobenhavn, p. 249. 
In the extreme tenuity of their bodily substance and their diaphan- 
ous delicacy of coloration, the ctenophores stand apart from other marine 
animals. Their presence in the water is commonly denoted only by the 
brilliant flash of rainbow colors which play along the lines of their cil- 
iary combs as they move languidly beneath the unrippled surface of 
the sea. Yet these creatures are no more wonderful in their complex 
organization than in their remarkable adjustment to their habitat, for 
so delicate are most of them that a current such as that of an oar suffices 
to tear them into misshapen shreds—a fate which they escape in time of 
storm by sinking far into the depths. This fact accounts for the extreme 
rarity of many of these forms, for the ocean’s surface must have remained 
flat as a mirror for many hours before they can be lured upward from the 
calm of their deep retreat. Yet tender as they are to the touch, passing 
jelly-like between the fingers of the hand that attempts to seize them,. 
their food consists largely of young fishes which they engulf in great 
numbers, seizing their prey by means of their peculiar ‘‘Greifzellen” (see 
Chun, 1880, Ctenophoren des Golfes von Neapel, p. 225, Taf. 18). Thus 
in the cold northern waters where ctenophores occur in vast swarms, 
