14 



BULLETIN 75, UNITED STATES NATIONAL MUSEUM. 



At depths exceeding 500 fathoms, sixteen additional species were 

 taken, which were not found at a less depth. They are: 



With the possible exception of Ophiotrochus, none of the genera in 

 this list are characteristically deep-water forms; all of the others occur 

 in less than 100 fathoms. While twelve species pass the 800-fathom 

 line, only two occur in water exceeding 1,000 fathoms; those two, it 

 will be noted, have a very remarkable bathymetrical range, one of 

 1,097, the other of 1,176 fathoms. In view of the considerable num- 

 ber of stations involved, the temperature range is very small, only 

 4.1 (39-34.9). 



Eighteen additional species occur only in water exceeding 300 

 fathoms in depth; eight of these extend into water exceeding 500 

 fathoms, but only two pass the 800-fathom line and they do not 

 reach 1,000 fathoms. The temperature range for these eighteen 

 species is 7.6 (42.9-35.3). 



At depths from 100 to 300 fathoms, forty-one species were taken, 

 of which sixteen were found below 300 fathoms, eleven below 500 

 but only two below 800. The temperature range in this group is 

 very great, over 30 (60.6-30.4), but for any one species the ex- 

 treme range is only about 12 (44.1-31.8), and for about two-thirds 

 of the species it is less than 5. 



There are fifty species which were taken between 50 and 100 

 fathoms; of these, forty- three extend their range beyond the 100- 

 fathom line, twenty-five beyond 300 fathoms, fifteen beyond 500, 

 six beyond 800, and four beyond 1,000. Naturally the temperature 

 range is extensive, 45 (75.4-30.4), though the extreme for any one 

 species is 25.3; one other species has a range exceeding 20 and 

 for seventeen others it exceeds 10. 



