1 1 
North Balabac Strait, 5S fathoms ("Albatross" Stat. 5356; Cat. X" 35275 I'. S. Nat. 
Mus.); 2 Ex. These have 15 and 21 arms. 
Verde Island Passage, i So fathoms ("Albatross" Stat. 5367; Cat. N" 36224 U.S. Nat. 
Mus.); I Ex. 
Near Marinduque, 106 fathoms ("Albatross" .Stat. 5369; Cat. N" 35949 U.S. Nat. .Mus.j; 
1 Ex. A typical example with 1 2 arms. 
Tawi Tawi group, 12 fathoms ("Albatross" Stat. 5154; Cat. N" 35270 U.S. Nat. Mus.j; 
I Ex. There are 19 arms. 
Zebu reefs, littoral (from the "Challenger" collection; Cat. N" 17529 U'.S. Nat. Mus.); 1 Ex. 
Decametra A. II. Clark. 
Key to the Species of the Genus Decametra. 
a' The distal edges of the segments of the much enlarged and stiffened P.,, which 
is from half again to twice as long as the approximately equal \\ and P., and 
is composed of 14 — 20 segments, bear groups of prominent spines at the 
prismatic angles; lower pinnules all stiffened; 16 — 20 cirrus segments; arms 
50 mm. long (so u t her n J apan) tigrina 
a'- The distal edges of the segments of P, do not bear groups of prominent spines 
at the prismatic angles; except for P.^ and sometimes P. (more rarely PJ the 
lower pinnules are not stiftened 
b' P„ resembling P, and longer than Pj; V„ with 15 — 17 segments 
c^ 20 — 23 cirrus segments; arms 65 mm. to 75 mm. long 
d' cirri stouter, the majority of the segments being twice as broad as 
long or even somewhat broader (Philippine Islands) . . . . mylitta 
d- cirri more slender, the majority of the segments being only slightly 
broader than long (K u r rach i, I n d ia) mollis 
c- 25 — 29 cirrus segments; arms 80 mm. to i 10 mm. long 
d^ P„ is stout, less than half again as long as P„ and none of its comp- 
onent segments are longer than broad (southwestern Indian 
Ocean) ahmdac 
d= P„ is rather slender, nearly or quite twice as long as Pj, and most of 
its component segments are from half again to twice as long as broad 
e^ mosV of the segments of P. are from one third to one half again 
as long as broad, with prominent, though not spinous, distal ends 
(Ceylon) taprobaiics 
e- most of the segments of P. are twice as long as broad, with spinous 
distal angles (M usca t, A rabi a) ara/>na 
h- P3 shorter than P, 
c' P„ has 17 — 18 smooth segments which do not bear spines on their distal 
angles; arms 45 mm. to 50 mm. long 
