418 Davis — On the Fossil Fish of the Cretaceous Formations of Scandinavia. 



character, so that where the specimens are not fragmentary, from the breaking of 

 the chalk, they are in few instances well preserved. The one represented on the 

 plate indicated above has a length from the snout to tlie base of the tail of 

 0*205 m., and the tail, which is not well represented on this or any of the other 

 specimens, is about an additional O-Oi m., which makes a total length of 0*245 m. 

 The greatest height, in front of the dorsal fin, is 0*065 m. ; thence the body 

 diminishes in height to the peduncle of the tail, which is about 0*025 m. in height. 

 The form of the body is an elongated oval, the posterior part tapering more 

 rapidly than the anterior. 



The head has a length of 0*08 m., and the height is 0*06 m. behind the orbit. 

 The mouth is large, with a wide gape. The pre-maxillary {p. mx.) is 0*025 m. in 

 length, dilated in front, and triangular behind. It bears a large number of 

 small, pointed, villiform teeth, slightly larger near the anterior extremity than 

 those behind. The maxilla [mx.) is long, anteriorly slender, but largely expanded 

 towards its distal extremity. It has no teeth. The anterior extremity of the 

 maxilla is attached to the vomer, and in the specimen (fig. 2, vom.) the anterior 

 portion of this bone is shown to bear teeth. The mandible [nin.) is large and of 

 robust proportions; the dentary [d) bears teeth similar to those of the pre-maxilla. 

 Its internal surface, exhibited by a fracture of the bone, is deeply channelled, for 

 the accommodation of the Meckel's cartilage; the articular portion of the mandible 

 is deep, and at its lower posterior extremity is a small bone which is probably the 

 angular. Above this the articular portion terminates in a coronoid process, 

 extending upwards, at right angles to the base. The orbit {or.) is large, and 

 occupies a forward position above the posterior extremity of the jaws. The bones 

 forming the orbit, except the pre-orbital (fig. 1, p. -or.) are not well defined; 

 neither can the elements composing the frontal or occipital regions of the head 

 be very clearly distinguished. The frontal bones are shown in the specimens 

 represented by all the figures, and those forming the upper posterior portion of 

 the head in figs. 1 and 2. The arrangement of the bones composing the opercular 

 covering is exhibited by figs. 1 and 3. The operculum (oj).) is large, with a 

 triangular posterior margin ; it was probably thin, and for this reason is not well- 

 preserved. It enveloped a portion of the body covered with scales. The sub- 

 operculum (s.-oj?.), attached to the lower extremity of the ojDerculum, is a semi- 

 triangular bone, with a rounded inferior margin. The pre-operculum [p.-op.), is 

 best preserved in sjDecimen fig. 3. It is a long bone, shaped like a boomerang, 

 with a sharp inclination forward on the anterior margin, at about one-third of its 

 height ; the posterior margin is finely serrated. The inter-operculum (figs. 2 and 3, 

 i.-op.) is an oblong bone, the upper margin concave, whilst the inferior one is 

 convex ; both this and the pre-operculum are thicker and stronger bones than the 

 remaining components of the gill- covers. The head represented by fig. 3 exhibits 



