ROLLING DOWNS FORMATION (CRETACEOUS) OF CENTRAL QUEENSLAND. 5 



and there are some superficial rugae in the lower half of the scale parallel with its 

 inferior border. The squamation above the principal flank series is partly shown in 

 the hinder half of the trunk, and some of the scales are well preserved (Fig. 6). 

 There are at least two series between the upper extremity of the principal scale and 

 the dorsal azygous series, both comprising imbricated rhomboidal scales, well 

 ornamented with rugfe of ganoine, and each with a prominent oblique ridge in the 

 middle of its exposed portion, almost diagonal ; the rugiB are partly concentric 

 with the hinder and inferior borders, partly at right angles to the former. Towards 

 the extremity of the tail the flank scales gradually become less deep in proportion 

 to their breadth, and at the origin of the caudal fin, all the scales of each ventral 

 row are of nearly equal size (Fig. 7), rhomboidal, and closely resembling the 

 ordinary dorso-lateral scales, except that the diagonal has become more prominent, 

 and few of the rugse are concentric with the borders. 



4. — Specific Determination. 



In the absence of definite information as to the proportions of the species now 

 described, it is necessary to refer exclusively to the scales for diagnostic characters. 

 It seems, however, almost certain that we are concerned with a much less slender 

 fish than the typical Jurassic species, Belonostomus temiirostris, B. sphyrcsnoides,* &c.; 

 while neither of these, so far as we can discover, exhibit so conspicuous and elaborate 

 a superficial ornamentation. It thus suffices to refer only to the known 

 Cretaceous species, which may be enumerated as follows : — 



Belonostomus attenuatus, Dixon, Geol. and Foss., Sussex, 1850, p. 368, PI. XXXV., 

 f. 4 [Portion of mandiblel , Chalk, Sussex. 



Belonostomus ductus, L. Agassiz, Poiss. Foss., 1844, Vol. II., Pt. II., p. 142, 



PI. LXVIrt, Figs. 10—13 ; F. Dixon, op. cit., p. 367, PI. XXXV., Fig. 3 ; 



A. S. Woodward, Quart. Jom-n. Geol. Soc, Vol. XLIV., p. 145, PL VII., 



Figs. 7—13, and Proc. Geol. Assoc, Vol. X., p. 305.— Chalk ; S.E. England. 



[Mandible and scales.] 



Belonostomus comptoui, Agassiz, A. S. Woodward, Proc. Zool. Soc, Nov. 18th, 

 1890. Aspidorhyuchus comptoui, L. Agassiz, Edin. New Phil. Journ., 

 1841, Vol. XXX., p. 83, and Comptes Eendus, 1844, Vol. XVIII., 

 p. 1009. — Upper Cretaceous ; Serra de Araripe, North Brazil. [Imperfect 

 fishes.] 



* L. Agassiz, I'oiss. Foss., II.. Piirt 2, p. 140 ; A. Wagner, Aljth. Math. Phys. CI. K. Akad. Wien, 1863, IX., 

 p. i'm. 



