34 BULLETIN 150, UNITED STATES NATIONAL MUSEUM 



TEMPERATURE 



The Liparidae thrive best and are most commonly found in tem- 

 peratures of less than 50° F. The tide-pool species are restricted in 

 their southern distribution by the summer isotherm of 60° F. It 

 is urdikely that any of the species are commonly found in such a high 

 temperature. The species attain the greatest size in the extremely 

 cold water of the northwestern Pacific, where they readily find a 

 temperature of 35° F. 



The temperatures inhabited by the bathybial and the shallow- 

 water species are about the same. The maximum and minimum 

 temperatures for the three large genera are as follows : Liparis, about 

 60° F. to 29.7° F.; Careproctus, 59° F. to 30° F.; Paraliparis, 52.8° F. 

 to 28° F. The deeper-water species of Liparis are usually taken 

 from a temperature of less than 45° F. Only one species of Care- 

 proctus has been reported from a temperature of more than 45° F. 

 The majority of the species are found in a temperature of about 

 40° F. This is true also of the species of Paraliparis. 



The regions inhabited by the deeper-water species probably are 

 not affected by the changing seasons and we may reasonably assume 

 that these species remain in a fairly constant temperature. Our 

 records do not indicate the range of temperature that can be endured 

 by the tide-pool species. Some of the deep-water species of Care- 

 proctus and Paraliparis have a range of temperature of 10° F. to 15° F. 

 It is likely that this is exceeded by the tide-pool species. 



SUMMARY 



It has been pointed out in the general discussion of the modifica- 

 tion of structure and the relation between the bathymetrical dis- 

 tribution and the coloration^ that the species of the deep-sea become 

 highly modified from the tide-pool type. The deep-sea forms have 

 digressed farthest from the primitive stock. It is attempted in the 

 following chart to present in a graphic manner the chief modifications 

 of structure and color as the species became adapted to the deep sea. 



It will be seen by an examination of the chart that in the deep-sea 

 species (1) the dorsal and anal rays increase in number; (2) the 

 pectoral and caudal rays decrease in number; (3) the pyloric coeca 

 decrease in number and are lost; (4) the gill slit is usually confined 

 to the region above the base of the pectoral fin; (5) the prickles 

 appear to be more common; (6) the pores are reduced in number; 

 (7) the disk is reduced and lost; (8) the eye increases in size; (9) the 

 connection between the vertical fins is increased; (10) the teeth 

 become simple and restricted in number; (11) the variegated colora- 

 tion is lost — the paitly black forms are the most numerous between 

 300 and 500 fathoms and the black forms are confined to the regions 

 below 400 fathoms. 



» Burke, 1911. 



