8 ROYAL SOCIETY OF CANADA 
A plate which appears to be one of the lateral cornua, terminating 
in a short spine is visible on the lower side of the body; it shows à 
pitted surface on the inside (probably corresponding to tubercles on the 
outside). In front of the middle of the head is a crescentic plate, 
also pitted on the inside; this may be the rostrum. Below, and near 
the head is a sheaf of three narrowly lanceolate plates, pitted on one 
side, with a number of strong spines attached to it converging to the 
plate. 
Fins.—From the head a dorsal fin appears to have extended back 
as far as opposite the anus, where it is replaced by a series of plates 
that go back as far as the body is preserved; there appears to have been 
no caudal fin on the upper side of the body within 35 mm. of the head, 
behind that the body is broken away. 
It will be noted that there are no fins visible along the lower side 
of the fish, this may be due to imperfect preservation; but from the 
anus toward the tail, as far as the body is preserved there are numerous 
close set, long, internal supporting spines, that indicate the presence of 
a heavy anal and lower caudal fin. 
Lying across the front of the body at the back of the head is a 
small, lanceolate, dark, granulated body, fringed with rays; this is 
probably the axis of a pectoral fin. 
Internal structure-——As in Phaneropleuron the ribs and ray-spines 
of this fish are well shown. The neural spines are numerous and closely 
set, but they are much shorter than in the two described species of 
Phaneropleuron, especially P. curtum, Whit., so the dorsal fin was of 
much less importance than it was in that species. The bases of the 
neural spines are stout and point forward; each base appears to cor- 
respond to two ribs directed backward. While the neural spines are 
short, as above mentioned, those that supported the muscles of the anal 
and lower caudal fin are numerous, strong and long; they are directed 
obliquely forward from below, and thus are nearly parallel to the outer 
parts of the ribs which are found in the front part of the body. 
Integument.—Beside the plates on the head above referred to there 
are plates on the back and belly. The middle and posterior part of 
the back (so far as it is preserved) carries a row (probably a double 
row) of small tuberculated plates; as only the edges of these plates 
are visible their form is not apparent. Along the ventral line from, the 
gullet to the anus there is on each side of the keel of the belly a row 
of about ten, oval ventral plates, these plates are rounded on the upper 
edge, but nearly straight along the ventral line; they appear to be 
smooth; a continuation of these plates, smaller and more obscure, ex- 
tend backward from the anus along the ventral line toward the tail. 
