Chap. III. GEOGRArillCAL DISTRIBUTION. 297 



SECTION V. 



GEOGRAPHICAL DISTRIBUTION OF THE CTEXOPHOR.E. 



The preceding enumeration may furnisli the means of tracing, to some extent, 

 the geographical range of the Ctenophoras, though it must Ije apparent, from a 

 survey of the locahties where Acalephs of this order have thus far been observed, 

 that much remains to be done before the laws which regulate their distribution can 

 be ascertained. One fact, however, is already plain, that there exist Ctenophoro3 in 

 all the oceans, and that they are as common in the arctic as in the temperate and 

 ti'opical seas; though the range of the different genei'a and species does not seem to 

 be more extensive or more limited than that of most marine animals. Peculiar genera 

 and sjjecies are known to be limited to certain parts of the ocean, while other genera 

 have a wider range and seem everywhere to have special representatives. The 

 Beroids proper are unquestionably^ the most widely distributed, species of this family 

 having been noticed under all latitudes and in every ocean. Next to them the 

 Saccata) have the most extensive range ; but among these there is already a marked 

 difference between different families, the Mertensida^ having a more northern range 

 than the Cydippidte proper. Indeed, the genus Mcrtensia is entirely arctic, while 

 the genera Martensia, Gegenbauria, and Owenia belong to the temjDcrate zone. 

 Pleurobrachia and Janira seem to be cosmopolite, Eschscholtzia and Ilormiphora are 

 the representatives of the same family in the temperate zone, while Dryodora is 

 arctic. The Callianiridas proper belong to the warm regions. The Taniataj are 

 entirely foreign to the cold climates, and seem to be more numerous in the tropical 

 i-egions than even in the temperate parts of the globe where they were first observed. 

 As to the Lobatiie, we find the family of Bolinida3 in the cold and temperate zones, 

 extending to the limits of the tropics ; while the Euramphajidir, the Mnemiidai, the 

 Caljaiimidoe, and the Ocyroida^ are almost exclusively tropical, and have only a few 

 representatives in the warmer temperate zones. 



If it were certain that the Beroidaj proper are the lowest Ctenophorce and the 

 Lobataj the highest, it would follow, that, on the whole, the lower representatives 

 of this order are the most widely distriljuted, and that the highest are more ex- 

 tensively found in the tropical regions, while those occupying an intermediate position 

 are either cosmopolites, or denizens of the temperate zone, or more tropical. It 

 seems at least to follow from the facts thus far ascertained, tliat the most elegant 

 and largest representatives of the Lobata?, such as Cliiaja and Leucothea, belong 

 to the warmer temperate and to the tropical zones, and that the most aberrant 

 VOL. III. 38 



