1897.] ECHIDNOCBPnAJiUS, A. HAIiOSAUKOID FISH. 269 



quadrate arcade, very slender in front and reaching forwards 

 almost as far as the symphysis of the mandible. The suspensorium 

 is obviously much inclined forwards. The quadrate (qu.) is 

 observed to be small and wedged between the ectopterygoid {ecpt.), 

 entopterygoid (enpt.), and metapterygoid (mj^t.). The mandible 

 (md.) is" long, elevated in the middle, and truncated at the 

 symphysis ; but although it articulates with the quadrate just 

 behind the middle point of the head, the gape of the mouth seems 

 to have been small, scarcely half the extent of the ramus entering 

 the oral border. A stout marginal bone of the upper jaw is 

 imperfectly shown sloping downwards and backwards from the 

 end of the rostrum to a point just behind the mandibular 

 symphysis, aud this may be interpreted as preraaxilla (pmx.). The 

 mouth must have been distinctly iuferior, the rostrum a little 

 prominent. Behind the skull there is the smooth impression of a 

 relatively small trapezoidal plate, which may be regarded as the 

 operculum (op.) ; but its antero-superior border is not clearly- 

 defined. Adjoining this plate at its antero-inferior margin is 

 another larger plat^ ornamented with fine, radiating strise, which 

 are evidently directed almost at right angles to its curved posterior 

 and inferior border. This bone exhibits no connection with the 

 mandibular suspensorium, which is considerably further forwards, 

 and its precise shape cannot be determined owing to a crush upon 

 the hyoid arch ; it is evidently the suboperculum (s.o^j.). Im- 

 pressions of nine slender and gently curved brauchiostegal rays 

 {br.) are shown, and are attached to a remnant probably of the 

 ceratohyal. The vertebrae are merely shown in impression, but 

 they are extremely numerous, while the centra are short and deep, 

 each marked by fine longitudinal ridges. The vertebral arches are 

 too delicate to be clearly observed. A delicate, curved, clavicular 

 bone (d.) occurs behind the opercular apparatus, but there are no 

 traces of the pectoral fins. The remains of the pelvic fins are also 

 too imperfect for description ; but the anterior rays of the short 

 dorsal, slightly further back, are beautifully shown. The foremost 

 ray seems to have been undivided, and is two-thirds as long as the 

 second. This also is not forked, but appears to have been 

 articulated at moderately wide intervals in the distal portion. 

 The third, fourth, and fifth rays not only exhibit distant articu- 

 lations, but also bifurcate twice in the distal portion. The 

 hinder rays are imperfect, the bases only of three being preserved. 

 The anal fin-supports are very short in proportion to the length of 

 the rays, and do not iuterdigitate with the more slender haemal 

 arches, which are incUned to the axis of the body at a much more 

 acute angle than they. The foremost anal fin-ray is undivided 

 and somewhat shorter than the next. The fifth ray exhibits one 

 bifurcation, but the impressions of the others, so far as distin- 

 guishable, are simple. No scales can be seen. 



Another specimen (Plate XVIII. fig. 2) displays the trunk 

 especially well in impression, with fragmentary remains of the head. 

 The articular end of the maudible (mcl.) is shown, with straight 

 inferior border, very low articulation, and the ramus rapidly rising 



