CHARACTERISTIC DEEP-SEA TYPES. — ACALEPHS. 129 
surface, moving from the bottom towards the surface, or even 
occasionally reaching it. 
Although many of the characteristic surface jelly-fishes have 
been mentioned in the general sketch of the Pelagie Fauna 
and Flora, a few deserve a more extended notice in the sys- 
tematie account of the group. Among the ctenophores I may 
mention a singular genus, Ocyroé, which has passed unnoticed 
for over fifty years, since its discovery in 1829. Unlike the 
other members of the group, it makes use of its large lateral 
lobes as flappers, and thus propels itself through the water with 
great rapidity. It is true that other ctenophores may, to a lim- 
ited extent, guide their movements by the gentle undulation of 
the lateral lobes of the body, but their principal means of loco- 
motion are the rows of locomotive flappers, or combs, from which 
the group derives its name. In Ocyroé the movement is pro- 
duced by the development of museular fibres on the inner sur- 
face of the lobes. Ocyroé is aiso noted for structural feat- 
ures of the highest interest. As has been observed by Dr. 
Fewkes, it combines characters which exist in the two groups 
into which the ctenophores have been divided. It stands inter- 
mediate between the 
groups, with marked 
characteristics of 
each. It is the only 
instance of a cten- 
ophore with lateral 
lobes not provided 
with tentacles. The 
spotted Ocyroé, O. 
maculata (Fig. 423), 
was noticed near St. 
Vincent ; and a spe- 
cies without spots, 
probably a young form, O. erystallina, was found at the Tor- 
bugas. 
One of the largest and most stately genera of tentaculated 
Fig. 423. — Ocyroé maculata. $. 
1 Dr. Fewkes has prepared the greater number of the descriptions of acalephs 
here given. 
