45 
Head and Opercular Apparatus. — The head is sliort and rounded, 
and the snout not produced to a point. The orbit is large, the month of 
moderate size, and the lower jaw stout. As usual, the exposed surfaces 
of the hones arc mostly destroyed, but there are indications of an ornament 
consisting both of small tubercles and striie. Of tlie cranial roof-bones, 
only the frontals are displayed in impression (PI. VI, Pig. 9), and these are 
very suggestive of the corresponding elements of the European Pholido- 
phorus.^ Por nearly half of their extent posteriorly they are relatively 
broad, but the outer lateral margin of each rapidly curves inwards in front, 
and the anterior third of the bone becomes narrow. Unless appearances in 
No. d arc deceptive, the maxilla is long and gently curved, exactly as in 
the typical Tholklophorns ; and it also bears a series of minute, conical, 
pointed teeth. In the mandible, the dentary bone is large and Ijroad, but 
its dentition is not clearly distinguishable. The post-orbital bones are large, 
at least two being well shown in No. e (PI. VI, Pig. 10) ; and the upper of 
these is quadrangular, about as long as deep, while the antero-inferior angle 
of the lower is so much produced forwards as to make it appear almost 
triangular. There is also a mark round the eye in this fossil, which may 
be either a narrow, regular, circumorbital ring, or merely an ossified sclerotic 
capsule. The opercular bones are narrow, but the divisional line between 
the operculum and sub-operculum is not very distinct ; this appears, hoAV- 
ever, to be oblique, and Avould thus correspond Avith that of the typical 
VlioUdophoriis. 
Axial Skeleton of Trunk. — There is distinct evidence of the persistence 
of the notochord, and this is but very slightly produced upAvards at its 
hinder extremity to form a superior caudal lobe. The neural and luemal 
arches must also have been imperfectly ossified, for nothing can be discerned 
as to their form and projAortions, even AAdiere the scales are removed. 
Appendicular Sketeton. — In the pectoral arch the clavicle is slender, 
and longitudinally striated, at least in its loAver portion ; and the type- 
specimen (PI. VI, Pig. 6) exhibits indications of two of the large post- 
clavicular scales. The pectoral fins are moderately poAverful, each consisting 
of about eight or nine rays, the first four or fiA*e especially stout, and the 
remainder more delicate and closely arranged (PI. VI, Pig. 6). The pelvic 
fins are small, each consisting probably of not more than five or six rays ; 
* L. Agassiz, Tomt cit., Ft. i, p. 286, PI, xlii a, tig. 5 (Pholidophorm minor' 
