1884.] MR. W. R. O. GRANT ON SICYDIUM AND LENTII'ES. lo3 



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. 

 GiJNTHER, F.R.S., V.P.Z.S.) 



[Eeceived 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 Cata- 

 logue, 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 mag- 

 nifying 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 iu 

 S. jnignans, 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 8. yymnogaster, n. sp., is figured ^Plate XII. fig. G), 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 oppor- 

 tunity of examining. In the fourth and last group, as in S. tccni- 

 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; Gunth. Cat. Fish. hi. p. 91 

 (part); Day, P. Linn. Soc. xiii. p. 140. 



Sicydium et Sicyopterus, Gill. Proc. Ac. Nat. Sc. Philad. 186*0, 

 p. 101. 



Proc. Zool. Soc— 1884, No. XL 11 



