380 
THE VOYAGE OF H.M.S. CHALLENGER. 
Scleritoderma, 
Adculites, .... 
Family Scleritodermidae, 
No. of Sp. 
No. of Oc. 
N. Atlantic. 
S. Atlantic. 
Indian Ocean. 
E. Pacific. 
W. Pacific. 
Antarctic and 
S. Indian. 
Locality (?). 
0-50 
61-200 
1 
201-1000 
1001 and over 
Depth (?). 
2 2 
1 1 
1 1 
1 1 
1 1 
1 1 
1 1 
1 1 
3 3 
2 2 
1 1 
2 2 
1 1 
Siphonidium, 
2 4 
1 3 
1 1 
2 2 
1 2 
Family Cladopeltidse, . 
2 4 
1 3 
1 1 
2 2 
1 2 
Azorica, .... 
4 10 
1 5 
1 1 
3 3 
1 1 
2 2 
2 2 
1 3 
3 3 
Trctolophus, 
1 1 
1 1 
1 1 
Gastrophanella, . 
1 3 
1 3 
1 2 
1 1 
Setidium, .... 
1 1 
1 1 
1 1 
1 1 
Poritella, .... 
1 1 
1 1 
1 1 
1 1 
Amphibleptula, . 
1 2 
1 2 
1 1 
1 1 
Tremaulidium, . 
1 1 
1 1 
1 1 
Leiodermatium, . 
1 2 
1 2 
1 2 
Sympyla, .... 
1 1 
1 1 
1 1 
Family Azoricidse, 
12 22 
8 16 
1 1 
4 4 
11 
2 2 
9 10 
4 6 
5 6 
Vetulina 
1 2 
1 2 
1 1 
1 1 
Family Anomocladidas, 
1 2 
1 2 
1 1 
1 1 
Total, 
294438 
140 238 
19 21 
39 40j84 106 
6 8 
11 14 
1011 
92124 
92112 
46 68 
6 11 
93131 
The thick figures in every case refer to the number of species, the thin to the number 
of recorded occurrences. Obviously, as the investigation of an area proceeds the number 
of recorded occurrences must tend to increase more rapidly than that of new species, and 
the ratio of species to occurrences should be less the more completely the fauna of a 
district is known ; this will appear from the table ; in the North Atlantic, for instance, 
the ratio of species to occurrences expressed as a percentage is 59, in the East Pacific 
79 ‘2, in the Indian Ocean 97 '5 ; in the remaining oceans the occurrences are not numerous 
enough to be of any statistical value. 
