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Show 884.] MR. W. R. O. GRANT ON SICYDIUM AND LENTIPES. 153 1. A Revision of the Fishes of the Genera Sicydium and Lentipes, with Descriptions of five new Species. By W . R. OGILVIE - GRANT. (Communicated by Dr. GUNTHER, F.R.S., V.P.Z.S.) [Received February 15, 1884.] (Plates XL, XII.) The fact that there are already as many as 19 species in the genus Sicydium (to which I have had to add 5) seems to justify an attempt to arrange the species into smaller groups, the members of which may be found to be allied together by some convenient and distinctive characters. Dr. Giinther, in his British Museum Catalogue, divides this genus into two groups according as the anterior teeth are, or are not, enlarged in the lower jaw. Making a further use of the line of investigation which he here opened to us, I have taken advantage of the opportunity of examining the characters of the teeth in the specimens in the British Museum. I find that the teeth of the upper jaw, when subjected to a magnifying power of some 200 diameters, are of one of four distinct forms, viz., unicuspid, bicuspid, and two kinds of tricuspid. In the first group, or that in which the teeth are unicuspid, and of which S. plumieri may be taken as typical, the teeth (Plate XII. fig. 5) are simple, slender, with the distal half bent inwards at or nearly at right angles. In the second, or bicuspid group, as in S. pugnans, n. sp., the teeth (Plate XII. fig. 7) are curved inwards and have their extremities bilobed and shaped like the anterior part of a pig's hoof. In the third group, as an example of which a tooth of S. gymnogaster, n. sp., is figured ^Plate XII. fig. 6), the teeth are tricuspid and trident-shaped, the lateral lobes long, the middle short and, as it were, suspended between the extremities of the former, so that it soon becomes worn away, and the tooth is then to all appearance bicuspid. I have not found these two last types of tooth in any as yet described species which I have had the opportunity of examining. In the fourth and last group, as in S. tani-urum, the teeth (Plate XII. fig. 8) are also tricuspid and trident-shaped ; but all the lobes being of nearly equal length and strength, the teeth retain this shape until quite worn down. SICYDIUM, C. & V. Sicydium, Cuv. & Val. xii. p. 167 ; Giinth. Cat. Fish. iii. p. (part) ; Day, P. Linn. Soc. xiii. p. 140. Sicydium et Sicyopterus, Gill. Proc. Ac. Nat. Sc. Philad. 1860, p. 101. PROC. ZOOL. Soc-1884, No. XI. 11 |
