184 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



The following table shows the range of the 174 species of Scypho- 

 medusae, not counting varieties, described in Mayer's Medusae of the 

 World. 



Confined to the Tropics 77 



Ranging from Tropics to Temperate regions 16 



Ranging from Tropical to Polar regions 2 



Confined to the North Temperate region 32 



Confined to the South Temperate region 11 



Ranging from Temperate to Polar seas 6 



Confined to the Arctic Ocean 7 



Confined to the Antarctic Ocean 7 



Deep sea medusae all of wide range 16 



Total 174 



In this table the Mediterranean is designated " North Temperate " 

 and the Red Sea " Tropical." In the " Tropics " the surface tempera- 

 ture in summer is above 70° F. (21° C). The summer temperature 



of " Temperate Region " ranges 

 from 70° F. to 50° (21° to 18° 

 C), and that of the " Polar Seas " 

 below 50° F. (10° C). 

 'i'/i^I r \ \ \ ^Uk) As is shown, 44 per cent of the 



mi jMlOll'il^Wn^^ known Scyphomedusae appear to 



be confined to tropical waters and 

 only two species, Aurellia aurita 

 by the author. Naples Zoological and possibly Nausithoe punctata 

 STATI0N - (fig. 1) range from Tropical to 



Polar Seas. Indeed most of the scyphomedusae are confined within 

 rather narrow temperature ranges, the only considerable number of 

 widely ranging forms being the deep sea species whose habitat has 

 about the same temperature whether under the Equator or in the 

 Polar regions. Incidentally the table seems to indicate our deficiency 

 of knowledge of the South Temperate regions for it is probable that 

 the numbers of species in the North Temperate are more nearly equal 

 to those found in the South Temperate Zone. 



We may distinguish five main divisions or orders of the larger 

 jelly fishes of scyphomedusae. 



1. The Carybdeidae or Cubomedusae, with bell almost rectangular 

 and with flexible tentacles mounted upon the ends of gelatinous wing- 

 shaped expansions. They have four knob-shaped sense-clubs, which 

 are very large and set within niches on the sides of the bell, with the 

 eyes all directed inward, apparently to command a view of the mouth. 

 These medusae have a marginal diaphragm which partially closes 

 the opening to the umbrella cavity. The Carybdeidae are confined 

 to tropical and warm seas and usually remain upon or near the bot- 



