REVIEW OF POLYIPNUS AND ARGYEOPELECUS — SOHULTZ 137 

 POLYIPNUS UNISPINUS, new species 



FiGUEE 43 



Holotype. — ^U.S.N.M. no. 103153, 20.5 mm in standard length, 

 Albatross station 5451, latitude 13°22'22'' N., longitude 124°00'48" 

 E., depth 380 fathoms, June 5, 1909. 



Paratypes. — Five specimens from the same collection, U.S.N.M. 

 no. 103029, 16 to 19 mm. 



Description, — The description is based on the holotype and the 

 five paratypes. The counts and measurements given outside the 

 parentheses were taken from the holotype, and those inside the 

 parentheses were taken from the 5 paratypes, respectively. All 

 measurements are expressed in hundredths of the standard length. 

 The dorsal fin is preceded by a pair of short diverging spines, the 

 number of dorsal soft rays are 12 (11, 12, 11, 12, 12) ; anal rays 14 

 (13, 14, 13, 14, 13) ; pelvic fin rays 7 (probably always 7) ; pectoral 

 rays 12 (13, — , 13, 15, 13) ; gill rakers on anterior margin of first 

 gill arch 4+8 (4+7, 4 + 7, 4+8, 4+7, 4+7) ; abdominal plates al- 

 ways 10. The lanterns (fig. 42) always occur in pairs on holotype 

 and paratypes in the following numbers : Branchiostegals always 6 ; 

 isthmus always 6; abdominals always 10; anals 12 (11, 13, 11, 11, 11), 

 the first two or three are much smaller than those that follow and 

 usually a trifle above the posterior ones; preanals always 5, the 

 first usually smaller than the 4 posterior ones ; suprapectorals always 

 3; subcaudals always 4; supra-abdominals always 3; preorbital al- 

 ways 1; subopercular always 1; lateral organ always 1, this is a 

 small photophore lying above the first preanal organ. Length of 

 head 31.6 (32.6, 30.3, 31.6, 30.6, 31.2) ; length of snout 7.8 (8.6, 8.3, 

 7.9, 7.1, 8.7) ; width of bony interorbital 5.9 (5.7, 5.6, 5.3, 5.9, 6.2) ; 

 horizontal diameter of eye 15.6 (17.2, 16.7, 15.8, 17.7, 16.9) ; length 

 from tip of snout to rear margin of maxillary 21.0 (24.2, 23.4, 22.6, 

 21.2, 21.9) ; length from snout to origin of soft dorsal 56.2 (57.2, 55.6, 

 60.5, 54.7, 52.0) ; greatest depth of body 48.8 (51.5, 50.0, 48.4, 53.0, 

 50.0) ; least depth of caudal peduncle 10.3 (9.7, 11.1, 10.5, 11.2, 11.3) ; 

 length of caudal peduncle 19.5 (17.2, 22.2, 21.2, 22.9, 18.8) ; length of 

 longest gill raker on first gill arch 7.8 (8.6, 8.3, 7.9, 8.8, 7.5) ; length 

 of abdomen 39.1 (34.3, 38.9, 33.2, 38.1, 34.4) ; distance from origin of 

 soft dorsal to base of caudal fin rays 44.0 (45.7, 47.3, 47.4, 47.1, 43.7) ; 

 length of the posttemporal (nuchal) process measured from nape to 

 posterior tip of the spine 22.0 (24.0, 23.4, 21.2, 20.6, 21.9). 



Remarks. — This new species differs from all other members of the 

 genus Polyipnus that lack the supra-anal organs by the single post- 

 temporal spine without serrations below and the fewer gill rakers, 

 4+7 or 8 instead of 7 to 10+12 to 18. The following synoptic 

 key, based upon specimens in the United States National Museum, 



