1904.] OSTEOLOGY OF CLUPEOID FISHES. 489 



lower edge of the fovanieu, but does not invariably do so. The 

 temporal foramen is reduced to a pin-point depression in Coilia, 

 and is wanting entii-ely in Ghanos. 



The pre-epiotic fossa, another Clupeoid feature, is a depression 

 ;it the side of the cranium, bounded by the epiotic, squamosal, and 

 parietal bones. It is wanting in Chanos ; in Coilia it is entii'ely 

 obliterated, and in Fristigaster and Ryperlop/ms lai-gely filled up 

 by the pi'ominent squamosal bulla. The pre-epiotic fossa is pro- 

 bably homologous with the "lateral cranial foramen" of the 

 Mormyi-oid fishes and Notojiteriis. The supratemporal bone lies 

 over the apertui-e of the fossa in the Clupeoid fishes, but being n 

 reduced bone it serves less obviously as a cover f oi- the fossa than 

 does the supratemporal for the foramen in the Mormyiida?. In 

 jYotopieras the supratemporal bone is redviced in size quite as 

 much as in the majority of the fishes now under consideration, 

 and more so than in Dussumieria. The pre-epiotic fossa, is 

 bounded by the parietal, epiotic, and squamosal, whereas the 

 foramen of Notopterus and the Mormyiidee is set a little lower 

 down, and is surrounded by the epiotic, squamosal, and exoccipital, 

 the parietal in these fishes occupying a position nearer the median 

 plane of the head, and being shut off fi-om the foramen by the 

 union of the squamosal with the epiotic. The suggestion is 

 strengthened by the fact that in Dassumieria the bottom of the 

 fossa is unossified and membranovis. If in the preparation of the 

 skull the membrane be removed, the fossa appears as a lar-ge 

 foi-amen leading into the ci-anial cavity. 



The lateral temporal gi-oove, situated above and behind the 

 postfrontal bone, is not well marked in the Clupeoid fishes, with 

 the exception of Chanos ; in most cases it is bi'oad and shallow, 

 and is barely recognisable as a groove. Thei'e is no subtemporal 

 fossa. The opisthotic bone is as a rule jjresent, but small ; it is 

 wanting in Engraidis and Coilia. 



The buUte in the pro-otic and squamosal bones for the lodgment 

 of cfecal diverticula of the swim-bladdei- are I'emarkably constant. 

 Both, however, are wanting in Chanos, and the squamosal bulla 

 is not present in Clu2Jea sprattus, although it occurs in the other 

 species of Clupea examined. The auditory fenestra, bounded by 

 the pi'o-otic, exoccipital, and basioccipital bones, is also a dis- 

 tinctive feature of the Clupeoids, although it occurs also in Hyodoit, 

 in which it is bounded by the same thi'ee bones. It is wanting 

 in Chanos and Coilia. The oi-bitosphenoid and basisphenoid bones 

 are variable in size ; both are wanting in Chanos. In Chipea, 

 Hyperlophus, Ghatoessus, and Dussumieria the orbitosphenoid 

 meets the prefrontal bones. 



The eye-muscle canal opens behind in all but Chanos and 

 Coilia, and except in these two genera and Chafoessus the para- 

 sphenoid is produced into a pair of posteriorly directed vertical 

 laminae of bone. In Chatoessus the vertical laminae are present 

 at the sides of the posterior opening of the eye-muscle canal, but 

 they are not produced backward into freely projecting wings. 



