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Show Works referred to. (1) H. G. S e e l e y : " On the Skeleton in new Cynodontia from the Karroo Rocks." Phil. Trans, vol. 186 11 p. 59 (1896). (2) H. G adow : ‘ Amphibia and Reptiles.' London, 1901. (3) H. G. S e e l e y : " On the Gomphodontia." Phil. Trans, vol. 186 B. p. 1 (1896). E XPLANATION OF PLATE X V I I I . Fig. 1. Occiput and upper cervical vertebrae of Gomphoynathus kannemeycri. Nat. size. Fig. 2. Under view of atlas and axis of G-omphognathus. Nat. size. Fig. 3. Posterior view of atlas &c. of Trirachodun kannemeyeri. Nat. size. Fig. 4. Under „ „ „ „ „ Nat. size. Fig. 5. Side „ „ „ „ ., Nat. size. at., atlas ; ax., axis ; e.o., exoccipital; h.at., hypapophysis of atlas; o.c., occipital condyle; o.p., odontoid process ; p.a., proatlas ; r 1, r4, ribs ; r.at., atlas rib; 7\ax., axis rib; sq., squamosal; z.at., zygapophysis of atlas; z.ax., zygapophysis of axis; 3c, 4c, 3rd and 4th cervical vertebrae. 4. A Revision of the Fishes of the Genus TriacantJius. By C. T a t e R e g a n , B .A .1 [Received January 20, 1903.] Although six species of Triacanthus were described and figured by Bleeker in the 4 Atlas Ichthyologique,' Gunther, in his Catalogue, recognized only three (viz.: Tr. strigilifer Cantor, biacideatus 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. biacideatus, and the fourth (Tr. nieuhofi) in that of Tr. brevirostris. 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 Plectognathi2, I examined the specimens of Triacanthi 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 Tr. macrurus is certainly identical with Tr. biacideatus Bl., a species not recognized by him; whilst a seventh species, which has been generally confused with Tr. brevirostris Schleg., is now described for the first time as Tr. 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. B oulenger, F.R.S., V.P.Z.S. 2 P. Z. S. 1902, ii. p. 284. 180 MR. C. TATE REGAN ON *TELE [Feb. 17, |