OCTOBEK 6, 1911] 



SCIENCE 



451 



peritoneum in the translucent species of Gare- 

 procius gives these fishes somewhat the ap- 

 pearance of having silvery sides. The dis- 

 tribution of the species having a silvery peri- 

 toneum apparently is not influenced by the 

 change in environment at the 273-fathom 

 level. 



The facts concerning the coloration and 

 distribution of the species of Careproctus in- 

 dicate that the 273-fathom level is of no 

 greater, if of as great, importance than the 

 400-fathom level in marking the border be- 

 tween two differently colored faunas. The 

 former level appears to be of little or no sig- 

 nificance in the distribution of the light- 

 colored species, while the latter level marks 

 the upward limit of distribution for the black 

 species and contains the largest number of 

 species intermediate between white and black, 

 i. 6., the dusky species. 



The genus Paraliparis in structure, colora- 

 tion and distribution is more of a deep-sea 

 genus than Careproctus. The species of the 

 genus may be placed in three color groups, 

 but the proportion of the species in the groups 

 difl'ers from that in Careproctus. For in- 

 stance only 8 per cent, of the species of Care- 

 proctus are black while 50 per cent, of the 

 species of Paraliparis are of this color. All 

 the species of Paraliparis have a dusky or 

 black peritoneum. Only 25 per cent, of the 

 species Careproctus have the peritoneum 

 black. The species of Paraliparis typically 



fathom level holds the same relation to the 

 distribution of the species of Paraliparis. "We 

 thus see that there is a difPerence of 200 fath- 

 oms between the centers of population of the 

 two genera. There must be considerable dif- 

 ference in the amount of light present at these 

 two centers of population. With this difPer- 

 ence in the amount of light is associated the 

 difference in the number of black forms in the 

 two genera. 



The relation between the coloration and the 

 distribution of the species of Paraliparis is 

 the same as" in Careproctus. Without enter- 

 ing into much detail we will state that the 

 273-fathom level is of no significance in the 

 distribution of the light-colored species. 

 Only two of these species have been taken 

 below this level. The distribution of the 

 black species is interesting because, as in 

 Careproctus, it extends from 400 fathoms 

 downward. 



The distribution of all the species of the 

 family reinforces the conclusions that may be 

 drawn from a study of the distribution of the 

 species of the genus Careproctus. The chart 

 indicates the coloration and distribution of all 

 the species. It can be seen that the 273- 

 fathom level marks the lower limit of distri- 

 bution for the variegated species, but is of no 

 significance in regard to the distribution of 

 the light-colored, dusky or black species. The 

 region at about 400 fathoms is of more im- 

 portance. It marks the depth at which the 



Depth 



Variegated. . 



Light 



Dusky 



Black 



30 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 3700 ISOO 1900 2000 



12! 11 



11 ill 



I 3 



Chart illustrating the eoloration and bathymetrieal distribution of the CyclogasteridcB. Species 

 ranging through depths represented by several sections are counted in each section. 



inhabit greater depths than do the species of 

 Careproctus. The high and low levels of dis- 

 tribution for the two genera are almost iden- 

 tical, but what may be termed the centers of 

 population of the two genera differ. Half of 

 the species of Careproctus are taken above and 

 half below the 300-fathom level. The 500- 



light-colored species are reduced in numbers, 

 and where the dusky species are the most 

 common. It also marks the upper limit of 

 distribution of the black species. 



The facts just stated indicate that, in gen- 

 eral, the eoloration of the species of Cyclo- 

 gasteridae depend upon their bathymetrieal 



