8 THE VOYAGE OF H.M.S. CHALLENGER. 
700 fathoms, A . Oorhynchus aucklandie, Hoek. 
825 : as é : Nymphon perlucidum, Hoek. 
1100 ° op : 4 Nymphon longicoxa, Hoek. 
‘ : A} : A Nymphon compactum, Hoek. 
1250 5 x , : Colossendeis minuta, Hoek. 
1375 : n : 5 Ascorhynchus glaber, Hoek. 
1375 to 1600 _,, : 5 Nymphon hamatum, Hoek. 
iS . of - ‘ Colossendeis gigas, Hoek. 
- 35 5 ; Colossendeis gracilis, Hoek. 
1600 to 1950 _,, “ ‘ Phowichilidium pilosum, Hoek. 
1675 5 " - : Nymphon meridionale, Hoek. 
+ 4 a 2 : Phowxichilidium oscitans, Hoek. 
1875 F o) : : Phoxichilidium mollissimum, Hoek. 
2160 - 5 : ; Nymphon procerum, Hoek. 
2225 IS ; 3 Nymphon longicollum, Hoek. 
ee : =F : 5 Collossendeis media, Hoek. 
2650 : $ a : Colossendeis brevipes, Hoek. 
The number of times at which Pycnogonida were dredged at certain depths is shown 
in the following table :— 
99 dredgings in depths of from lto 500 fathoms, . : 26 times. Y 
30 5 3 501 to 1000 so, : : a) > 
47 7 5 1001 to 1500 =, 2 Ee 3} op 
47 x, op 1501 to 2000 _—S—,, : : A 55 
93 5 x 2001 to 2500 _—ti, 3 : Ph 
83 ” ” 2501 to 3000 =» - . Once (at 2650 fathoms). 
11 = Ay 3001 to 4575 35 ; ; None. : 
It thus becomes apparent that what Davidson has shown for the Brachiopoda, 
holds also in the case of the Pycnogonida, that they are very seldom found in depths 
exceeding 500 fathoms ; out of about 100-dredgings in depths of from 1 to 500 fathoms, 
Pycnogonids were brought up twenty-six times, while in depths varying from 501 to 
3000, they were obtained only thirteen times out of 300 dredgings. 
The following statement shows the range in depth at which the genera of Pyenogonida 
hitherto known have been found. The total number is twenty-seven genera, of which 
eleven are true littoral forms. Of the sixteen remaining genera there are five 
of which I am quite uncertain as to the depth at which they are found, and 
four for which the depth does not exceed 50 fathoms. Then there are two (Pallene 
and Pycnogonum), which, as a rule, inhahit depths not exceeding 120 fathoms, but 
which in a single case were found at depths almost reaching 500 fathoms (Pallene 
malleolata, G. O. Sars, at a depth varying between 191 and 459 fathoms, and Pyeno- 
gonum litorale, dredged by Smith and Harger, at a depth of 430 fathoms). Hence 
there remain only five genera of Pycnogonida, species of which may truly be called 
deep-sea inhabitants; they are the genera Nymphon, Ascorhynchus, Oorhynchus, Colos- 
sendeis, and Phowichilidium. 
