180 MR. C. TATE REGAN ON THE (ctor 
Works referred to. 
(1) H. G. Srerey: “On the Skeleton in new Cynodontia from 
the Karroo Rocks.” Phil. Trans. vol. 186 B. p. 59 (1896). 
(2) H.Gapow: ‘ Amphibia and Reptiles.’ London, 1901. 
(3) H.G.Sreney: “On the Gomphodontia,” Phil. Trans. vol. 186 B. 
p. 1 (1896). 
EXPLANATION OF PLATE XVIII. 
Fig. 1. Occiput and upper cervical vertebra of Gomphognathus kannemeyeri. Nat. 
size. 
Fig. 2. Under view of atlas and axis of Gomphognathus. Nat. size. 
Fig. 3. Posterior view of atlas &c. of Drivachodon kannemeyeri. Nat. size. 
Fig. 4. Under Baill ess 55 a Be Nat. size. 
Fig. 5. Side Penne 3 # Ss Nat. size. 
at., atlas; ax., axis; e.0., exoccipital; h.at., hypapophysis of atlas; 0.c., occipital 
condyle; o.p., odontoid process; p.a., proatlas; 7°, r4, bs; 7.a¢., atlas rib; r.aa., 
axis rib; sq., squamosal ; z.a¢., zygapophysis of atlas; z.aa., zygapophysis of axis; 
8c, 4c, 3rd and 4th cervical vertebra. 
4. A Revision of the Fishes of the Genus Triacanthus. 
By C. Tarn Reean, B.A 
[Received January 20, 1903.] 
Although six species of 7riacanthus were described and figured 
by Bleeker in the ‘ Atlas Ichthyologique,’ Giinther, in his Catalogue, 
recognized only three (viz.: Zr. strigilifer Cantor, biaculeatus 
Bloch, and brevirostris Schlegel), and did not accept either of the 
four described by Dr. Bleeker as new, but placed three of them 
(viz.: Tr. macrurus, blochi, and oxycephalus) in the synonymy of 
Tr. biaculeatus, and the fourth (77. niewhoft) in that of 7%. brevi- 
rostris. Since then this arrangement has not been challenged, nor 
has any new species of this genus been described. 
Subsequent to the reading of my paper on the Plectognathi?, I 
examined the specimens of Zriacanthi in the British Museum 
Collection, which include Bleeker’s types, and I have come to 
the conclusion that all six species described by Bleeker are valid, 
although the one he called 7'r. macrurus is certainly identical with 
Tr. biaculeatus Bl., a specigs not recognized by him; whilst a 
seventh species, which has been generally confused with 7'r. brevi- 
rostris Schleg., is now described for the first time as 7’r. indicus. 
A complete revision of the synonymy has thus become necessary, 
and the need for more complete diagnoses of the various species is 
obvious. In the descriptions given below, which are in each case 
based on several specimens, the total length is measured to the 
base of the first caudal ray, the length of head to the gill-opening, 
the length of the caudal peduncle from the base of the last dorsal 
to that of the first caudal ray, the length of the snout from its tip 
to the vertical from the anterior margin of the eye, that of the 
1 Communicated by G. A. BouLENGER, F.R.S., V.P.Z.S. 
2 P.Z.S. 1902, ii. p. 284. 
