38 CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 



Ocyropsis crystallina. (Figs. 55, 56, plate 10.) 



Ocyroe crystalliiia, Rang, 1828, Mem. Soc. Nat. Paris, tome 4, p. 172, plate 20, 

 fig. 4. — Fewkes, 1882, Bull. Mus. Comp. Zool. at Harvard College, vol. 9, 

 No. 7, p. 252, plate I, figs. 1-6. — Mayer, 1900, Ibid., vol. 37, p. 81, plate 31, 

 fig. 105. — MosER, 1903, Ctenophoren der 5t6oga-Expedition, p. 17. 



Mature animal: (Text-figure 11.) The oral-aboral axis is about 

 45 mm. long, and this is also the length of each oral lobe. The body is 

 laterally compressed, the width in the direction of the oral lobes being 

 about three times as great as that of the transverse axis. The 8 rows 

 of ciliated plates are short and the plates are few in number. The 4 

 subtentacular rows are only about two-thirds as long as the 4 subventral 

 rows. Each subauricular row contains about 20 and each subventral row 



Fig. II. — Ocyropsis crystallina. Adult, i, natural size. 

 Tortugas, Florida. 



about 40 ciliary plates. The cilia contribute but little to aid the animal 

 in swimming, this being accomplished almost entirely by the flapping 

 movements of the large, powerful, oral lobes, which by their periodic 

 closure drive the animal forward. After two or three closures of the 

 distended lobes there is usually a brief period of rest, followed by several 

 more movements. A powerful system of radiating and circular muscles is 

 found in the oral lobes and the flapping movements are caused by their 

 contraction and expansion. The lobes are i . 5 times as wide as they are 

 long. The simple apical sense-organ is sunken at the bottom of a shallow 

 cleft. The auricles are each about 30 mm. in length, flat, and ribbon- 

 like. Their narrow edges are lined with long cilia. Upon the outer 

 surface of the oral lobes, immediately over the longitudinal meridional 



