CHARACTERISTIC DEEP-SEA TYPES. — STARFISHES. 107 
There exists in Archaster mirabilis (Fig. 386) a remark- 
able sort of pedicellarie, 
consisting of two ossicles 
placed face to face like the 
hooks of a bracket, each 
carrying a comb of spines 
falling one towards the 
other and forming a very 
complicated organ of pre- 
hension. 
There seems to be no 
doubt that the starfish 
fauna becomes less and less 
varied as the depth in- 
creases, the maximum de- 
velopment in individuals 
being found at a depth of 
from 100 to 250 fathoms. 
The number of species 
does not seem to diminish 
so rapidly as the number 
of individuals, nor in pro- 
portion to the variation of Fig. 380. — Archaster mirabilis. 4. (Perrier.) 
the nature of the bottom. 
Thus in depths of less than 100 fathoms it required 2.7 hauls 
of the dredge to bring up one species, 15 species and 150 speci- 
mens being collected in 41 hauls. Between 100 and 200 fath- 
oms, 21 species and 144 specimens being obtained, the coeffi- 
cient was 3.6. From 200 to 300 fathoms the coefficient was 
3.15, with 13 species and 66 individuals. From 300 to 400 fath- 
oms only 12 individuals were dredged, belonging to 9 species, 
the coefficient being 3.9. Between 400 and 500 fathoms the 
coeffieient was 4.6. Between 500 and 600 fathoms the coeffi- 
cient had become 13. We made 15 hauls between 800 and 900 
fathoms, but obtained only 3 species and 3 individuals, although 
at a depth of 1,900 to 2,000 fathoms, 4 hauls gave us 7 speci- 
mens of 4 species. 
Of course the method of carrying on dredgings affects the 
