Clupeoid Fish from tha KtiijUsh Chalk. ;i25 



of an antorbital i.s proscrvcl (tig. 2, ii.o.^, hut this is iiitei- 

 esting as cxhihitiiig ilownwarilly-riidiating branches fi-otn the 

 slime-canal which traverses it. There are remains of the two 

 large siipraniaxilh'e [s.mx.) overlapping the maxilla {mx), of 

 which the convex oral border is beset with minute teeth. The 

 rather stout promaxillai must clearly have met in the middle 

 line, and that of the riglit side exhibits a considerably 

 extended oral face with the bases of attachment for a cluster 

 of minute teeth. The mandible {md.) is fragmentary, but 

 its articulation is shown beneath the hinder border of the 

 orbit. The deep and narrow [)reoperculum [p-^p-) lif^s a 

 straijiht vortical anterior niarjrin which is somewhat thick- 

 cned. The lower lin^b of this bone is small, an<l from its 

 angle there are a few radiating lidges. 'i'he o|)erculum (^/>.) 

 is delicate and deeper than broad, and a few of the charac- 

 teristic cycloidal scales extend both over this bone and over 

 the cheek. Of the trunk only the lower portion is preserved, 

 but this is comjdcfe to the base of the caudal fin (c). There 

 aie remains of the comjiarativcly small pectoral fins {pet.) 

 well on the flank, while the bases of the very stout pelvic 

 fins (ph'.) are seen on the somewhat flattened ventral aspect 

 slightly further back. Each of the latter comprises at least 

 eight or nine robust rays, of which only the undivided 

 proximal ends are preserved. The anal fin (a.) is small, 

 arising about midway between the pelvic and caudal fins. 

 The cycloidal scales are rather thick, and merely exhibit the 

 concentric lines of growth without any posterior crenulations 

 or serrations. 



Comparing the specimen now described with those in the 

 British Museum which were referred to Aniolepis ti/pus in 

 LSl'O, it is evident that only those numbered 47932 and 

 P. 4247 were ri-htly determined. Nos. 49903, P. 1854, and 

 P. 5681 probably belong to a small species of Osmeroides^ 

 which will be discussed in part iv. of the British ]\Iuseum 

 * Catalogue of Fossil Fishes.' It now appears that the skull 

 of Aulo/epis is intermediate in characters between that of the 

 tyj)ical EK'pidai and that of the typical Clupeidaj. The 

 snj)raocci|)ital bone enters the cranial roof, though not com- 

 }»letcly .^ejiarating the parietals, while the lateral muscles of 

 the trunk must have extended well forwards over the sides of 

 the skull above the laterally projecting otic region. There is 

 no evidence of a gular plate ; indeed it was probably absent, 

 for the branchi(-stegal rays are distinctly few in number. 

 'J'he jaws are typically Olupeoid. The trunk is conijiara- 

 tively short, much latt-rally compressed, and covered with 

 rather large cycloid iicalcs, while the fius are exactly as 



