398 bulletin: museum of comparative zoology. 



GEOGRAPHICAL DISTRIBUTION. 



Moser's ( : 09) recent discussion of the geographical distribution of 

 the Ctenophores is so thorough that it will no doubt form the starting 

 point for all future work along this line, and Mayer ( : 12) has given 

 a valuable account of the occurrence of the group on the east coast 

 of North America. But inasmuch as the Eastern Tropical Pacific, 

 so far as its Ctenophores are concerned, was practically a blank on the 

 map, until visited by the "Albatross," our records are of considerable 

 importance in their relation to Moser's general conclusions. They 

 help to fill in a very large geographic gap. There were only two species, 

 viz., Hormiphora palmata and Beroc forskalii, which occurred often 

 enough to show the regularity of their distribution within the area 

 examined. The former was taken on all our lines, and its occurrences 

 (Plate 2) were sufficiently numerous to show that it is a characteristic 

 and typical member of the pelagic fauna of the Eastern Tropical 

 Pacific. It is noteworthy that it was not encountered in the colder 

 waters of the Humboldt Current close to the Peruvian coast, on either 

 of our two southern lines. This may have been a coincidence; in- 

 deed, equally broad gaps may be seen on other lines. But it is an 

 interesting fact that it was not the only common surface form found 

 on all our lines, but absent from the cold-coast water traversed on the 

 two southern sections of the Humboldt Current. Practically the 

 same distribution was true of several Siphonophores (Bigelow, :11). 



Moser's record of H. palmata (= "japomca") from Japan is espe- 

 cially interesting because so far as the locality, Sagami Bay, shows, it 

 might belong to either the cold- or the warm-water fauna. The 

 oceanographic conditions along the east coast of Japan have been 

 explained in a very lucid way by Doflein (:06), who himself noticed 

 a startlingly rapid and complete change in the surface fauna in Sagami 

 Bay from days when the warm waters (22-24° C.) of the Kuroshiwo 

 Current swept into it, to others when they were replaced by cold 

 water (15-18° C.) after north and northwest winds. In the former 

 case he collected a typical tropical fauna, including such genera as 

 Cestum, Porpita, Forskalea, Physalia, Janthina, Philliroe, and Cari- 

 naria. In the latter these were entirely lacking and in their places 

 were found northern copepods and diatoms. 



Now, in turning to Moser's ( : 08a) list of Japanese Ctenophores 

 collected by Doflein, we find that Cestum was taken at the same 

 locality, and on the same date as Hormiphora. And the "Albatross" 



