54 BULLETIN 150, UNITED STATES NATIONAL MUSEUM 



has been little or no migration across the Kamchatka Channel in 

 recent times. The deep water acts as a barrier to the adults, and the 

 eggs are probably endemic or fastened to the seaweed or rocks. 



It is interesting to note that the majority of the American species 

 inhabit the tide pools and that a large majority of the Asiatic species 

 come from greater depths. This may be explained as only apparent 

 because of the lack of a thorough exploration of the Siberian coast, or, 

 that failing, to the longer stretch of favorable coast line reaching from 

 central California to the Aleutian Islands and northern Alaska. 



Regions. — We may conveniently divide the species of this genus into 

 four groups which inhabit different geographical regions. These 

 regions may be termed Asiatic, Pacific American, North Atlantic, and 

 South American. The species of each region, with a few possible 

 exceptions, are distinct. The Asiatic region contains 10, the Pacific 

 American 14, the North Atlantic 5, and the South American 2 species. 



The Pacific American region can be divided into two sub regions — 

 (1) northern California to the Aleutian Islands, (2) coast of Alaska 

 north of the peninsula to the Arctic Ocean. The first of these regions 

 conforms with the first three regions given by Evermann and Golds- 

 borough (1907-222), and the second in a general way with the fourth 

 and fifth. Certain species extend nearly throughout the first subregion 

 or practically 20° of latitude. L. mucosus inhabits the shore line from 

 Pacific Grove to Kodiak Island; L. pulchellus from San Francisco Bay 

 to Bristol Bay; L. callyodon, P. heringianus, and P. greeni from the 

 northern coast of Washington to Bering Island. None of the Asiatic 

 or North Atlantic soecies are known to range through so many degrees 

 of latitude. 



The Alaska Peninsula apparently serves as a barrier to the deeper- 

 water species. None of these are known from both sides of this 

 barrier. 



The deeper-water species are not known to have a greater range 

 than the tide-pool species. Liparis fucensis and L. dennyi have the 

 greatest range and extent from the coast of Washington to the Gulf 

 of Alaska. 



Distribution of closely related species. — Our knowledge of the rela- 

 tionships of the species of Liparis is too incomplete to draw any final 

 conclusions concerning the distribution of closely related species, but 

 what evidence there is is of interest to anyone testing the law stated 

 by Jordan as, "given any species in any region, the nearest related 

 species is not likely to be found in the same nor in a remote region, 

 but in a neighboring district separated from the first by a barrier of 

 some sort." The genus Liparis can be divided into groups of closely 

 related species and species which are isolated in their relationships. 

 The groups of related species and their distribution are as follows : 



