36 CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 



Florida form. I here give the dimensions of a small specimen from 

 Naples, because it corresponds more nearly in size to those found at 

 Tortugas. 



Total length 



Width of body above oral lobes in tentacular diam- 

 eter 



Width of body above oral lobes in sagittal diameter 

 Width across expanded lobes 



Length of auricles (approximate) 40 



Length of stomodEeum 44 



Depth of sense-organ cleft 10 16 



Length of body from aboral apex to mouth 58 72 



Length from aboral apex to origin of oral lobes .... 39 45 



General color j Transparent with 4 ; Dull translucent 



yellow spots upon , brownish without 

 oral lobes. yellow spots on 



oral lobes. 



Leucothea ochracea 

 from Tortugas. 



96 



20 



33 



no 



Leucothea 



multicornis 



from Naples. 



88 



26 



41 



85 not fully 



expanded. 



It is somewhat surprising to find these marked differences between 

 the Mediterranean and the Tortugas forms of Leucothea, for it has long 

 been known that the Mediterranean form is widely spread over the warm 

 parts of the Eastern Atlantic and has been recorded from the Canaries, 

 Azores, and South Equatorial Stream. Fewkes, 1882, observed the 

 Florida Leucothea and states that it is more transparent than the Medi- 

 terranean form. This statement is true if we except the 4 opaque yellow 

 spots in the gelatinous substance of its oral lobes, which in so far as I 

 Jiave observed appear always to be present. 



The Florida species is not common and comes to the surface in num- 

 ■bers only when the ocean is unrippled after days of calm. The least 

 breeze suffices to produce sufficient rippling to cause it to sink into the 

 •depths. In this habit it resembles Leucothea grandiformis of the Fiji 

 Islands. The Fijian form is, however, anatomically speaking, more 

 nearly allied to the Mediterranean species. It is remarkable that the 

 Mediterranean Leucothea appears to be far less troubled by waves and 

 is often found quite near the surface in fairly rough weather. The ex- 

 treme tenuity of this Florida ctenophore is remarkable, for even a gentle 

 (Current suffices to tear it apart. I have seen it only in spring and summer 

 at Tortugas. 



But little stress should be laid upon the presence of the 4 yellow 

 areas upon the lobes of the Tortugas Leucothea and we may neglect it 

 as a specific character ; for it is possible that this yellow coloration may 

 be due to commensal plant-cells. Unfortunately since this point occurred 

 to me I have been unable to find any specimens of the ctenophore. 

 Indeed, Fewkes appears to have found specimens of Leucothea in Florida 

 waters which lacked these yellow areas and were quite transparent. 

 Some specimens of Folia at Tortugas have yellow spots at the ends of 

 the long axis of the body, while others are wholly transparent. In Cestum 

 amphitrites from the Pacific there are, according to the figures of Mertens, 

 1833, and Bigelow, 1904, yellow spots at the tips of the long axis of the 

 body. (See Cestum pectenalis, Bigelow, 1904, Bull. Museum Comp. Zool. 



