50 FOSSIL FISHES OF THE ENGLISH CHALK. 



Generic Characters. — Trunk rather deeply fusiform, hoth this aud the head 

 laterally compressed. Cranial roof exhibiting a median longitudinal depression, its 

 lateral and occipital margins ornamented, like the other external bones, with ridges 

 and tubercles of ganoine. Mandible a little prominent, with several rows of recurved 

 conical teeth, irregular in size and arrangement ; premaxilla long and slender, with 

 one or more rows of minute teeth ; maxilla long and slender, underlapped by the 

 premaxilla for the greater part of its length, but entering the gape behind, where 

 it bears a spaced series of relatively large conical teeth pointing forwards ; a 

 conspicuous supramaxilla present ; the comparatively stout palatine and ectoptery- 

 goid bones bearing a close series of acute, laterally compressed teeth, which are 

 largest in the middle and diminish towards each extremity; no teeth barbed. 

 Preoperculum very narrow and deep, with a conspicuous posteriorly directed spine 

 at its lower end ; operculum strengthened on the inner side by a ridge extending 

 almost horizontally backwards to its postero-inferior angle ; branchiostegal rays 

 about 15 in number. Vertebrae from 35 to 45 in number, the centra at least as 

 long as deep, much constricted mesially and somewhat strengthened with small 

 longitudinal ridges. Fin-rays robust and all articulated, mostly also subdivided 

 distally ; no fin-rays excessively elongated. Paired fins large, the pelvic pair not 

 much smaller than the pectorals ; the short dorsal fin within the anterior half of 

 the trunk; anal fin relatively small and remote; caudal fin deeply forked. 

 Enlarged dermal scutes restricted to the end of the tail. 



Tyije Species. — Halec sternbergi (L. Agassiz, ' Poiss. Foss.,' vol. v, pt. ii, 1844, 

 p. 123, pi. Ixiii), from the Turonian of Bohemia. 



Remarks. — The fish from the English Chalk commonly known as Pomognathus, 

 is proved by direct comparison of specimens to be generically identical with Halec, 

 which was inadequately described by Agassiz from the Bohemian Chalk. It also 

 agrees in the characters of the head and fins with the so-called riiylactoceplialus, 

 from the Upper Cretaceous of Mount Lebanon and Dalmatia, which is only 

 distinguished by its smaller number of vertebrge (35) and by its covering of minute 

 scales. Tlie latter difference, however, may be more apparent than real, considering 

 the nature of the matrix in which the English fossils occur. Archgeogadus 

 guestphalicns, from the Pliinerkalk of Dortmund, certainly belongs to Halec, as 

 shown by the type specimen in the Academy of Miinster, Westphalia. 



L Halec eupterygius (Dixon). Plate XIII ; Text-figure 11. 



1837. Osmeroides lewesiensis, L. Agassiz, Poiss. Foss., vol. v, pi. Ix h, figs. 3, 4 (errore). 

 (?) 1844. Osmeroides granulatus, L. Agassiz, ibid., vol. v, pt. i, p. 14 (uame only). 

 1850. Pomognathus eupterygius, F. Dixon, Gool. Sussex, p. 367, pi. xxxv, figs. 6, 7. 

 1888. Pomognathus eupterygivs, A. S. Woodward, Proc. Geol. Assoc, vol. x, p. 318. 

 1901. Halec eupterygius, A. S. Woodward, Calal. Foss. Fishes B. M., pt. iv, p. 213. 



