from the English Lower Lias. 431 



width, and with less radiating markings. In short, the more 

 important known facts in the skeletal anatomy of this fish 

 may now be summarized as follows : — 



Trunk fusiform, robust, and somewhat elongated. Man- 

 dibular suspensorium oblique ; dentition consisting of an 

 inner series of large conical teeth, well spaced but numerous, 

 and an outer close series of smaller teeth, similar in form ; 

 head, opercular, and branchiostegal bones externally tuber- 

 culated or rugose. Fins large, consisting of broad, flattened 

 rays, all articulated and distally bifurcating, more or less 

 coated with ganoine ; anterior borders fringed with well- 

 developed fulcra. Dorsal and anal fins triangular in shape, 

 elevated, the dorsal opposed to the space between the pelvic 

 fins and the anal. Scales thick, of moderate size, and highly 

 ornamented ; not much deeper than broad upon the middle of 

 the flank, as deep as broad on the ventral aspect. Each 

 scale of the abdominal region marked in its hinder half by 

 coarse postero-inferiorly directed ridges and sharp denticula- 

 tions, in its anterior half by few, irregular, more or less 

 interrupted vertical ridges and furrows ; the scales of the 

 caudal region coarsely serrated posteriorly, with a few short, 

 transverse sculpturings anteriorly. 



Genus OXYGNATHUS. 



The facts made known in Egerton's description of Oxy- 

 gnathus suffice to demonstrate the right of the type species 

 to generic distinction, although the " diagnosis " is as unsatis- 

 factory as most of those in early palajichthyological writings. 

 The figure (Egerton's pi. ix.), however, exhibits some inac- 

 curacies, the pectoral fin-rays being unarticulated except at 

 the extremities, as correctly noted in the description ; the 

 striations upon the jaws not being regular parallel lines, but 

 short and wavy fine ridges, irregularly anastomosing and 

 bifurcating ; while the supposed indications of " ossified 

 vertebras " are either small pleurocentra and hypocentra, or, 

 as seems more probable, merely the expanded bases of the 

 arches. 



A new diagnosis of the genus, based upon the original 

 description and the examination of the large series of exam- 

 ples in the British Museum, may thus be enunciated in the 

 following terms : — 



Trunk elegantly fusiform, more or less elongated. Mandi- 

 bular suspensorium oblique ; dentition consisting of a series 

 of large, well-spaced conical teeth, and numerous minute 

 teeth irregularly arranged and somewhat clustered; cranial 

 roof-bones finely tuberculated, sometimes rugose, the facial 



