448 DR. W. G. RIDEWOOD ON THE CRANIAL [DeC. 13, 



5. On the Cranial Osteology o£ the Clupeoid Fishes. By 

 W. G. RiDEWOOD, D.Sc, F.Z.S., Lecturer on Biology 

 at St, Mary's Hospital Medical School, London. 



[Received November 11, 1904.J 



(Text-figures 118-143.) 



Introduction. 



In the spring of 1896, Prof. G. B. Howes suggested to me 

 that an investigation on the structure of the skull in the lower 

 Teleostean fishes would be a profitable piece of research, since 

 there was every prospect of the results proving a valuable means 

 of testing the validity of the existing schemes of classification of 

 the fishes in question, and because an accurate knowledge of the 

 structure of the skull in the lower Teleostean fishes was essential 

 to a successful study of the remains of those extremely interesting 

 extinct fishes which lie on the boundary-line between the Tele- 

 osteans aiad the Ganoids. 



The investigation has proceeded slowly and intermittently, 

 owing to repeated interruptions and to pressure of other work ; 

 but sufficient progress has now been made to allow of the publica- 

 tion of some of the results. Descriptions of the skulls of Elops, 

 Megalops, and Albula, togethei- with some general observations on 

 the Teleostean skull, have already appeared in the ' Proceedings 

 of the Zoological Society,' 1904, ii. pp. 35-81, and observations 

 on the cranial osteology of the Mormyridte, Notopteridse, and 

 Hyodontidee in the Journal of the Linnean Society, xxix. 1904, 

 pp. 188-217. A third paper, on the skull of the Osteoglossidse, 

 Pantodontidse, and Phractolaemidse, has just been completed, and 

 has been offered to the Linnean Society ; the present contribution 

 deals with the skull of the Clupeoid fishes. 



Eleven genera are considered in this paper, namely : — Chiro- 

 centrus, Chtpea, Pellona, Pellonula, Pristig aster, Hyjierlophus, 

 Chatoessus, Bussumieria, Engraulis, Coilia, aud Ghanos. A 

 " Summary " of the observations and some " Comments " thereon 

 are given on pp. 488-493. 



Skulls of Ghirocentrus, Clupea, Chatoessus, Engraulis, Coilia, 

 and Chanos were specially prepared for the purposes of the 

 investigation, and were disarticulated according to the method 

 explained in the ' Proceedings of the Zoological Society,' 1904, ii. 

 p. 36 ; the other skulls examined are the propei'ty of the British 

 Museum, and I take this opportunity of acknowledging my 

 indebtedness to Mr. G. A. Boulenger for offering to me every 

 facility in his power for the examination of the skulls under 

 his charge. 



Chirocentrus dorab. 



The only published figure of the skull of Ghirocentrus that 

 I have been able to discover is a not very serviceable sketch of 



