GEOGRAPHICAL DISTRIBUTION. 371 



liaul (-lOO-U m.), and at that Station the temperature at 200 m. was only 56° 6. 

 The two "Siboga" records were from even deeper hauls (1,000-0 m., and 1,500- 

 m. respectively). None of these records, then, suggest that the species is 

 common in very high temperatures. And the same is true of the series col- 

 lected by the "Albatross," for the species was not found at all on the surface, 

 but always in intermediate hauls, though the surface temperatures at the six 

 stations of capture were all below 75°. 



Physophora is common on the surface in the Mediterranean during the 

 winter, when the temperature falls to about 57°; but during the hot months it 

 disappears from the surface (p. 380). In the Atlantic this species extends far 

 northward. It is known from the coast of Scotland; is not uncommon on the 

 Norwegian coast as far north as 71°. A list of its boreal occurrences has been 

 given by Romer ( : 02) ; and since the appearance of his paper, the genus has been 

 recorded from the south and west coasts of Iceland by Paulsen (: 09). But since 

 it is not known from Spitzbergen, and since the Duke of Orleans did not encounter 

 it in the Greenland Sea, it probably does not occur in temperatures lower than 45°. 

 In short, the various records of the species shows that it is at home neither in 

 the Arctic, nor in the hottest tropical temperatures. 



Agalma elegans is also found through a wide range of temperatures, i. e. 

 tropics to Norway (p. 283). Nectalia loligo, likewise, has been taken at the 

 Canaries, at a temperature of about 68° (Haeckel, January) ; south of Iceland 

 (60° 2' N., 22° 7' W. ; Chun, '97b) at a temperature of 46° and in a closing-net haul 

 at 600-800 m. in the south equatorial current (3° 6' S., 33° 2' W.), a level at 

 which the temperature was below 50°. The only other Siphonophores which have 

 been credited with a distribution reaching from the tropics to the Subarctic 

 zone are Galeolaria biloba and Muggiaea atlantica. But as already pointed out 

 the identity of the former with G. australis of the Tropical Indo-Pacific is open 

 to question (p. 234), and Broch (:08) has recently shown that the records 

 of M. atlantica from the Skagerak by .lohansen and Levinsen ( : 03) probably 

 belong to Diphyes arctica. At present it is doubtful whether any Siphonophore 

 is truly eurythermal, but if Stephanomia cura and »S'. bijuga finally prove to be 

 identical, they would afford a typical example of this class of distribution. 



All the other Siphonophores which are yet known from the surface belong 

 to warm-temperate or to tropical regions, the two supposed Antarctic records 

 (Rennie, : 05 and Bedot, : 08) being respectively the tentacle of a Scyphome- 

 dusa, and an Anthomedusa (Browne, :10). 



