DESCRIPTION OF THE SPECIES OF PTERYGOTUS 211 
the first joint, at least in the var. plicatiss’mus, fig. 16, and it is 
probably so in all species, 
The sculpture in the body rings, fig. 13 a, extends over less than 
half their surface. The plice are open forwards, very small, almost 
linear on the front margin (the extreme margin of all the segments 
is rounded off and smooth) and the remainder are less than semi- 
circles or they are subangular (more than 90°), On each side at 
they are not as wide. A transverse impressed line separates the 
anterior sculptured half from the posterior smooth portion, but this is 
not always present. No crenate edge has yet been observed. 
Appendages, Plate XV. [Plate 26] fig. 2. 
On a specimen much distorted, and from which the swimming 
foot, Plate I. [Plate 12] fig. 13*, is taken, the following organs may 
be detected by careful examination :— 
Epistoma, /, reflected from the under side. 
Antenne, 6, 0’. 
Great post-oral plate or metastoma, ¢. 
Two endognaths, ¢, ¢’, with palpi +. 
Endognath (mandible or maxilla) of the opposite side, c”. 
A separate jointed palpus. 
Ectognath (swimming foot), e, attached to the carapace. 
First body joint. 
Ff The large epistomian plate resembles much in shape that seen 
in Plate I. [Plate 12] fig. 1 @, which is similarly displaced. We 
only see a portion of it, the termination being broken off, but it 
appears to have been semicircular and semioval, more than three- 
fourths the width of the carapace, and covered with minute promi- 
nent plicae, Near its base, but not attached, are remains of a single 
antenna, 0. 
b, &', Antenna—Only the general form can be made out; it 
is thick in proportion to the size of the specimen, and consists of 
apparently only three joints, the lower one broken (4), the fragment 
three times as long as wide; the second (é’), crossed by a line, 
which is probably a fracture, appears to be a long single joint, five 
times as wide as long, its articulation with the neighbouring joints 
being marked by small irregular crenulations. The penultimate 
joint or fixed finger 4” is much crushed, it seems to be contracted 
at its base, the lower part barrel shaped, about twice as wide as 
long, and tapering rather gradually into the serrate portion. The 
P 2 
