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BuUetin //, V)iitcd States National Mtisemn. 



741. GYMNOCANTHUS, Swainson. 



Oymnocanthus, Swainson, Class. Fisli., etc., 11, 271, 1839 {ventralis). 



Phobetor, Kkoyer, Naturli. Tidschr., i, 2(33, 1844 (tricuspis). 



Elaphocottus, Sauvage, Nouv. Arch. Mus. Paris (2), I, 1878, U2 (pistilliger) . 



General characters and appearance of Acanthocottiis, but with no teeth 

 on the vomer, the slit behind the last gill small or wanting ; upper pre- 

 opercular spine stout, armed with 2 or 3 antler-like processes ; fins all very 

 large, the veutrals notably so. Arctic Seas, {yi'i.ivoi, naked; czHavOa, 

 spine.) 



a. Interorbital space not armed with bony granulations; males with a round white 



spot on belly; last gill arch without .slit or pore. 



b. Dorsal rays X, 14 or 1.5; anal 16; a cirrus behind eye in young; occipital ridge 



with 3 bony prominences ; axial region in male with fringed filaments, white 



at tip. PISTU.LIGER, 2375. 



bb. Dorsal rays XII, 16; anal 18; no cirrus behind eye; occiput without bony 



prominences; axial region without fringed filament.* in either sex. 



TRICUSPIS, 2376. 



aa. Interorbital region covered with bony granulations: males without white spots on 



belly; dorsal rays XI, 16; anall9. galeatus, 2377. 



•2375. (JYMXOCAXTHUS PISTILLIGER (PaUas). 



Dr. Gilbert describes this species as follows: 



"Compared with Gy7nnocaiithus ti-icuspis, G. pistiUiger has a difterent fin 

 formula, the spines and rays of dorsal and anal fins being fewer in number. 

 This is shown l)y the following table, based on an examination of 40 

 specimens : 



" The normal formula may therefore be given : D. IX or X, 14 or 15 ; A. 16 

 or 17. The type of G. jnstUlUjer is said to have D. IX, 13; A. 16; and its 

 synonyms, G. renU-alis, Cuvier &, Valenciennes, and 6?. intermedins, Tem- 

 minck & Schlegel, have, respectively, D. IX, 13 ; A. 17 ; and D. IX, 13 ; A. 14. 

 In G. tricitsi)is the formula is D. XI or XII (rarely X), 15 to 17; A. 16 to 19. 

 The dorsal fins are more widely separated in G. pistUUger, where the inter- 

 space is equal to \ or more than l the diameter of the pupil. The verte- 

 bra' are fewer in number, 12 + 24 instead of 12 + 28. In G. pistilUger a,\i 

 obtuse prominence aI)Ove hinder margin of orbit bears in young indi- 

 viduals a slender cirrus, which frequently disappears in adults. Behind 

 the eye, a continuous occipital ridge bears 3 smaller bony prominences, 

 the first immediately behind the eye, the second and third approximated 

 at posterior end of ridge ; these bear no cirri. G. tricuspis has no tubercles 

 on occiput. In males of G. pistilliger, the post axial region is furnished 

 with a number of very slender filaments, each of which is expanded at tip 



