125 



Prometra A. H. Clark. 

 Key to the Species of the Genus Prometra. 



a 1 The first three pinnules are of the same length and character, but P 4 and the 

 following pinnules are much shorter 



b 1 16 — 21 (usually 18 — 19), cirrus segments; P x — P s with 14—16 segments; 



arm length 55 mm. to 60 mm. (southern Ja'pan) owstoni 



b 2 14 — 15 cirrus segments; P x — P :; with 11 — 12 segments; arm length about 



30 mm. (Philippinelslands) longipinna 



a 2 The first three pinnules are not of the same length 



b 1 P 2 greatly elongated, becoming very slender and almost flagellate distally, 

 nearly twice as long as P l and P 3 , which are of the same length, com- 

 posed of 21 segments; arm length 90 mm.; cirri with 22 — 24 segments 



(Red Se a) chadzvicki 



b 2 Pj is longer than P 2 , which otherwise exactly resembles it; both are 

 composed of 8 segments; arm length 18 mm.; cirri with 10 — 11 segments 

 (Andaman Islands) intermcdia x ) 



1. Prometra longipinna sp. nov. 



This species closely resembles P. oivstoni; it may be briefiy diagnosed as follows: 

 The cirri have 14 — 15 segments of which the fourth and following are about as long 

 as broad; the cirrus length is about 4 mm. 



The arms are about 30 mm. long, resembling those of P. owstoni, 



Pj is 5 mm. long, stiff and spine-like, composed of 11 — 12 segments of which the first 

 is broader than long, the second one third again as long as broad, and the fourth and following 

 two and one half to three times as long as broad ; the terminal three or four have prominently 

 spinous distal ends. P 3 is 5 mm. long with 11 — 12 segments, exactly resembling P r P 3 is 

 5 mm. long with 1 1 segments of which the outer are slightly more elongate than those of the 

 preceding pinnules, and the fourth and following have everted and spinous distal ends. P t and 

 the following pinnules are 3.5 mm. long with 10 segments, smaller and weaker than the 

 preceding pinnules, though the component segments are of about the same proportions; the 

 fourth and following have everted and spinous distal ends. The distal pinnules are 4.5 mm. 

 long with 14 segments of which the third and following have slightly produced and finely 

 spinous distal ends. 



The single specimen at hand was dredged in North Balabac Strait, Philippine Islands, 

 in 58 fathoms ("Albatross" Stat. 5356; Cat. N° 35366 U.S. Nat. Mus.). 



No species of this genus was secured by the "Siboga", but it is desirable here to 

 include a notice of it as it is one of the characteristic genera of the Indo-Pacific fauna. 



1) Oligometra inttrmedia A. H. Clark, 1912. 



