336 Mr. J. W. Davis on a new Species of Ptycholepis. 
convex; the mouth is large, apparently extending far towards 
the anterior extremity of the operculum; the snout projects a 
short distance beyond the mouth ; the orbit is well developed, 
occupying an area one fifth the length of the head and about 
its own diameter distant from the end of the snout. The 
bones of the head are well preserved, and are ornamented with 
the enamelled ridges characteristic of the genus. The opercu- 
jJum—unlike that of P. bollensts, which is smooth, or P. curtus, 
which is anteriorly ornamented by widely separated ridges, 
whilst on the posterior portion they are nearly obsolete—in this 
specimen is deeply channelled, the shining ridges standing i 
high relief over the whole surface, but without any apparently 
definite arrangement. Along the inner or basal margin of 
the operculum there is a narrow strip, separated by a deep 
groove, which is perfectly smooth. The suboperculum is 
comparatively small; it is similarly decorated and possesses 
a smooth strip along the margin next the operculum. The 
bones of the cranium, as well as those of the jaws, are orna-~ 
mented with a series of more or less parallel ridges, which 
anteriorly bend with a sinuous curvature so as to encircle the 
nasal extremity. 
The scales on the body are larger anteriorly than those 
nearer the tail; they are arranged in symmetrical parallel 
rows, each about ‘1 inch in length and extending more or 
less diagonally from the dorsal towards the ventral surface. 
The scales of the dorsal part of the body are wider than those 
of the ventral. The enlarged figure (Pl. X. fig. 1 a) repre- 
sents a scale midway across the body and *5 inch behind the 
operculum ; fig. 1¢ is taken from the ventral surface at °S 
inch behind the pectoral fin, and 16 is from the surface 
near the tail. The posterior margin of all the scales is deeply 
serrated ; the number of serrations varies with the width of the 
scales, and corresponding to them are depressions of the sur- 
face or grooves, deepest at the anterior margin and extending 
towards, but rarely attaining, the posterior one. The base of 
each scale has a number of transverse imbrications, delicately 
marked and only distinguishable when highly magnified. 
The dorsal jin is indicated by a faint impression of some of 
the fin-rays. It appears to be situated slightly in advance of 
the ventral fins, but not so much so as in Ptycholepis curtus, 
Eeert. The pectoral fins are situated immediately behind 
the head; they are well developed, nearly an inch in length, 
consisting of about twenty rays. ‘The rays are grooved near 
the base, but afterwards dichotomizing towards the margin ; 
the transverse articulations are clearly discernible at about 
half an inch from the base of the fin, and may be distinguished 
