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 Pelagic Fauna 

 and Flora, a few deserve a more extended notice in the sys- 

 tematic account of the group. Among the ctenophores I may 

 mention a singular genus, Ocyroe, 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 Ocyroe the movement is pro- 

 duced by the development of muscular fibres on the inner sur- 

 face of the lobes. Ocyroe is also noted for structural feat- 

 ures of the highest interest. As has been observed by Dr. 

 Fewkes, 1 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 o f 

 each. It is the only 

 instance of a cten- 

 ophore with lateral 

 lobes not provided 

 with tentacles. The 

 spotted Ocyroe, O. 

 maculata (Fig. 423), 

 was noticed near St. 

 Vincent ; and a spe- 



.., Fig-. 423. Ocyroe maculata. \. 



cies without spots, 



probably a young form, 0. crystalline^ was found at the Tor- 



tugas. 



One of the largest and most stately genera of tentaculated 



1 Dr. Fewkes has prepared the greater number of the descriptions of acalephs 

 here given. 



