400 bulletin: museum of comparative zoology. 



six years ago, Moser ( : 09) has already recorded it from the tropical 

 Atlantic, the south Atlantic, and the neighborhood of Cape Town. 

 And it is not only the wide separation of these localities which is 

 striking, but the fact that the few records yet obtained already extend 

 its temperature range from 58.6° F. to 79° F. is even more important 

 as showing over how broad a range it may be expected. I may like- 

 wise emphasize the occurrence of Pleurobrachia pileus in Acapulco 

 Harbor, at a temperature of 83° F. Moser ( : 09) speaks of this species 

 as a northern form, and uses this as an argument against uniting 

 Graeffe's Pleurobrachia from Trieste with it. When a species occurs 

 from the Arctic to lat. 34° N. in the north Atlantic; along the west 

 coast of America from Puget Sound to Acapulco, at the Seychelles; at 

 various South African localities, and very generally in the Antarctic; 

 when it thus runs through the entire gamut of oceanic temperatures, 

 it would not be surprising to find it anywhere. And, as a matter of 

 fact, it does occur in the Mediterranean (p. 372). It is truly cosmo- 

 politan, as it is classified in Moser's list. But though its range reaches 

 from pole to pole, it is a much more important constituent of the 

 Arctic and Subarctic than of the tropical plankton. In the colder 

 Atlantic currents it is regular in occurrence, and often extremely 

 numerous; in the tropics it is recorded only occasionally, and usually 

 from small specimens. 



The "Aloatross" discovered no local species of Ctenophores. All 

 her captures extend the range of previously known forms, but they 

 afford some evidence that at least one genus, Cestum, has one tropical 

 species in the Indo-Pacific, another in the Atlantic; though the case 

 is not yet altogether clear. There is no evident reason why this 

 should be the case, when one species of Hormiphora extends over both 

 oceans, but I may point out that there is an Atlantic and a Pacific 

 species of Physalia, of Porpita, and probably of Velella, whereas most 

 tropical Siphonophores are cosmopolitan in waters of suitable tempera- 

 tures. 



To sum up: — the "Albatross" collection lends important support 

 to Moser's generalization that the Ctenophores as a whole are animals 

 of wide distribution; and it reduces by one, Pleurobrachia rhodopsis, 

 the list of forms so far known only from restricted localities. It also 

 rescues from obscurity one of the old species, Cestum amphitrides 

 Mertens. 



In the accompanying map (Plate 2) the occurrence of Ctenophores is 

 plotted for the eastern half of the Pacific, only records of the specific 

 identity of which there is no reasonable doubt being included. For 





