60 ACANTHOPTERYGII. 



Trigla Icevis, Montagu, Mem. Wern. Soo. ii, pt. 2, p, 455 ; Flem. Brit. Anim. 

 p. 214, sp. 148; Swainson, Fishes, ii, p. 420; Embleton, Berwick. Nat. Field 

 Club, 1831, p. 22. 



Trigla corvus, Eisso, Hist. Nat. iii, p, 398. 



Trigla oorax, Bonap. Faun. Ital. Pesci, t. f. 1. 



Trigla paxiloptera (Young'), Cuv. and Val. iv, p. 47 ; Yarrell, Brit. Fishes 

 (Ed. 2) i, p. 49, c. fig. (Ed. 3) ii, p. 24 ; Swainson, ii, p. 262 ; Thompson, 

 Proo. Zool. Soc. 1837, p. 61, and Nat. Hist. Ireland, iy, p. 79 ; Demid. Voy. 

 Russ. Merid. iii, p. 375 ; Guichen. Explor. Alger. Poiss. p. 39 ; "White, Oatal. Brit. 

 Fish. p. 3 ; Walker, Zool. 1859, p. 6540 ; Giinther, Catal. ii, p. 203 ; Couch, Brit. 

 Fish, ii, p. 36, pi. Ixx, f. 2. 



Tnhfish, Couch, Fish. Brit. Isles, ii, p. 21, pi. ixv. 



B. vii, D. 9/16-17. P. 10 + iii, V. 1/6. A. 15-16, C. 12. Ccec. pyl. 10, Vert. 

 14-15/19. 



Length of head 3| to 4, of caudal fin 4| to 5|, height of body 6 to 65 in the 

 total length. Uye — Ij to 1|^ diameters in the postorbital portion of the head, 

 2 diameters from the end of the snout, and 1 diameter apart. Interorbital space 

 deeply concave. Upper profile from eyes to snout, with a slight descent. Bones 

 of the head with stellated ridges, which are least developed between the eyes. 

 Several spinate denticulations at the anterior-superior angle of the orbit. Pre- 

 orbital granulated anteriorly, even serrated in some examples and in the young : 

 angle of preopercle acute, and in the young there are two sharp spines. 

 Supra-scapular roughened, ending posteriorly in a short and sharp spine. Coraooid 

 with a roughened ridge passing across it and ending in a spine : all these spines 

 are more developed in the young than in the adult, and they diifer in their 

 extent in adult examples. In the yoang a strong ridge ending in a spine passes 

 across the opercle : while the occiput has two spines posteriorly. The posterior 

 extremity of the maxilla almost reaches to beneath the front edge of the eye. 

 Teeth — ^fine ones in the jaws and on the vomer : none on the palatines or tongue. 

 Fins — first dorsal spines almost or quite smooth anteriorly, the second the longest 

 and equal to the length of the snout : rays of the second dorsal scarcely more 

 than half as high as the first dorsal, and some are divided at their extremities. 

 Pectoral longer than the head (this is subject to variation) and reaching to above 

 the seventh anal ray. Caudal emarginate. Scales — small, nearly 200 irregular 

 rows descend towards the lateral-line, the scales of which are unarmed. From 25 

 to 27 spinate plates along the base of the dorsal fins. Air-hladder — large, trilobed 

 all of equal length in the adult, anteriorly they communicate freely with one 

 another. Anteriorly the air-vessel is produced into two short horns : the outer 

 wall is very muscular. In the young, the lateral lobes are very short but they 

 gradually increase in length with the age of the fish. According to M. Moreau 

 (Comptes Rendus, 1864, t. lix, p. 436), the air-bladder is furnished with thick and 

 strong muscles of the striped or voluntary kind. Two large nerves pass to 

 it from the upper part of the spinal cord close to the first pair of dorsal nerves 

 and below the pneumo gas trio. The mucous membrane which lines the internal 

 surface of the air-bladder forms a fold or diaphragm which subdivides this cavity 

 into two secondary chambers, communicating by an aperture in this partition, 

 which has some function analagous to ,that of the pupil of the eye : as under 

 the microscope it is seen to be provided with sphincter-like muscular fibres 

 disposed concentrically to the opening, while others radially arranged pass at a 

 tangent from them. Both sets of muscular fibres are smooth and presumably of 

 the involuntary variety. In August, 1863, a section of the spinal cord above the 

 dorsal region was made in one of these fish while still living, the abdomen 

 was opened and a feeble galvanic current passed to the nerves proceeding to 

 the air-bladder. Sounds similar to those emitted during life were immediately 

 produced audible to persons standing at some distance. A current was next 

 applied to the muscle of the air-bladder but without any result. Next a window 

 was cut in the lower portion of the air-bladder so as to expose the diaphragm, and 

 galvanism being applied, it was seen to be thrown into a state of vibration but no 



