18 CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 
meridional vessels are wide and their edges exhibit a wavy outline, prob- 
ably due to contraction. The 2 paragastric vessels are well developed and 
closely pressed to the sides of the stomodeum. They flare outward at 
the level of the mouth. The 2 tentacular canals are very short and the 
tentacle bases small, but the sheaths are correspondingly long and extend 
downward and finally outward, to open very near the mouth at about 
the level of the oral ends of the meridional canals. I have never seen 
the tentacles protrude beyond the sheaths, but they appear to have 
lateral filaments. 
I have not seen the genital products and can not state that the 
specimens were mature, for the dull milky color of this animal renders 
it only about as translucent as ground glass, so that minute details of 
its internal structure can be seen only with difficulty. It is rare and I 
have seen only 4 specimens between May and July at Tortugas, Florida. 
It comes to the surface only when the water has been calm and unrippled 
for some hours. 
Order LOBAT L. Agassiz, 1860. 
Beroide lobate, EscuscuHoutz, 1825, Isis, p. 741. 
Mnemiide, EscuscHourz, 1829, Syst. der Acal., p. 29. 
Callianiride, MERTENS, 1833, Mém. Acad. St. Pétersbourg, sér. 6, tome 2, p- 495. 
Calymmide, GEGENBAUR, 1856, Archiv fiir Naturges., Jahrg. 22, Pp. 192. 
Lobate, Acassiz, L., 1860, Cont. Nat. Hist. U. S., vol. 3, pp. 199, 289.—AGassiz, 
A., 1865, North Amer. Acal., p. 14.—CuuN, 1880, Ctenophoren Golfes von 
Neapel, p. 287, 1898, Ctenophoren der Plankton-Expedition, p. 22.—Van- 
HOFFEN, 1906, Nordisches Plankton, Ctenophoren, p. 4.—MosEr, 1903, Cteno- 
eborsn der Plankton-Expedition, p. 16; also, 1908, Abhandl. Akad. Mtinchen, 
uppl. Bd. 1, Abhandl. 4, p. 36; also 1, 1909, Ctenophoren der deutsche Stid- 
polar-Exped., Bd. 11, Zool. 3, p. 161. 
CHARACTERS OF THE LOBATA. 
The body is laterally compressed, the gastric axis through the stomo- 
dzum and oral lobes being longer than the funnel-axis through the lateral 
tentacles. There are 2 oral lobes, 1 on each side of the mouth. At the 
lower ends of each of the subtentacular combs of cilia there are 4 freely 
projecting, ribbon-like auricles which are fringed along their narrow 
edges with cilia. The 4 principal, interradial, entodermal canals spring 
directly from the funnel. The meridional canal-system communicates 
with the |-shaped oral ends of the 2 paragastric tubes and also winds 
in a more or less complex manner in the substance of the oral lobes. 
The tentacle bases are near the oral pole. There are no tentacle-sheaths. 
The larva passes through a Mertensia-like stage, and in Leucothea 
the animal may become sexually mature while in this condition. 
It is evident that the Lobatz are derived from the Cydippide and 
that they came from Mertensia-like ancestors. 
It is interesting also to see that the Cestide are closely related to 
the Lobate, and the canal-systems of the Cestide and Beroide are some- 
what similar each to each in their general features. 
