492 ALTERS: [ VOL. Te 
usually only one or two pores in this group; but in the 27-inch 
specimen there were six on one side and five on the other, all 
lying along the edge of the crease. As already stated, this 
group lies close to group 5 infra-orbital, the two being separated 
by the crease. There were two openings in the nasal bone 
corresponding to this group. 
Group 2 has usually four pores, which form a slightly curved 
line, extending backward and medianward from the anterior 
edge of the nasal tube, and lying nearly in the line of the 
hind edge of the ethmoid. The group is a prominent one, 
and is most regular and constant in shape and position. In 
the 27-inch specimen it contained seven pores on each side of 
the head, all arranged in line as usual; but on the left side the 
median pore of the group, which approached closely the ante- 
rior pore of group 3, was dividing at right angles to the line of 
the group, the new pore lying in front of the line of the rest of 
the pores. In the 17-inch specimen the lateral pore of the 
group, on the right side, had undergone a complete division at 
right angles to the line of the group. These two instances 
were the only ones noted of a pore lying out of the regular line. 
Group 3 lies near the middle line of the head, directly above 
the nasal sack. In the 17-inch specimen it had nineteen pores ; 
in the 20-inch one, twenty-four ; and in the 27-inch one a still 
greater number; but in this specimen the group was so continu- 
ous with groups 4 supra-orbital and 6 infra-orbital that the exact 
number of pores in each could not be determined. 
The double group, 4 supra-orbital and 6 infra-orbital, lies close 
to the posterior naris. A part of the pores lie in a half-circle 
along the median edge of the aperture, and the rest of them 
form two groups, one lying in front of and median to the aper- 
ture, and the other behind and median to it, or directly behind 
it. This last group belongs entirely to system 4 supra-orbital, 
and the other entirely to system 6 infra-orbital ; while the half 
circle of pores belongs partly to each of these systems. The 
group is usually continuous with group 5 supra-orbital. In the 
17-inch specimen it had twenty-eight pores; in the 201-inch © 
one, twenty-four ; and in the 27-inch one, a much larger number, 
but it was so continuous with groups 3 and 5 that the number 
of pores could not be determined. The two systems lie almost 
entirely in the dermis, so that in the skull there were only five 
