256 Port IL1—Twelfth Annual Report 
antenns nine-jointed, and bearing long slender sete. The proportional 
lengths of the joints are shown in the formula :— 
1518 ABO Bice SG bea 
PotD ko 08e tae cee IG Keo nmna ae: 
The secondary branches are composed of two moderately long joints. 
Mandibles with the oblique biting edge coarsely serrate. Mandible-palp 
with a moderately large, stout, basal part, and two small branches (fig. 16). 
Maxilla-palp with three small narrow branches, each bearing two to three 
slender apical sete (fig. 17). Posterior foot-jaws short, moderately stout ; 
the last joint somewhat ovate, bearing a slender seta near the middle of 
the inner margin. Terminal claw slender, gently curved (fig. 19). The 
first pair of swimming-feet slender. Inner branches considerably longer 
than the outer. The inner terminal claw of both branches is comparatively 
very long and slender (fig. 20). In the fourth pair the inner branches 
reach slightly beyond the second joint of the outer branches. The last joint 
of the inner branches is about equal to three-fourths of the entire length 
of the other two joints, and the length of the last joint of the outer 
branches is nearly equal to that of the first and second together (fig. 21). 
The basal joints of the fifth pair are broadly triangular, and the apex 
reaches to near the middle of the secondary joints. They are furnished with 
three plumose sete on the inner distal margin, and a moderately long ter- 
minal and small sub-terminal sete. Secondary joints sub-cylindrical, and 
bearing eight setee,—three on the inner and;three on the outer distal mar- . 
gin, and two at the apex. Both margins of both joints are fringed with cilia 
(fig. 23). Caudal stylets very short. All the body segments are fringed 
with cilia round the posterior margin. 
Male.—Anterior antenne apparently eight jointed, hinged between the 
second and third and between the fifth and sixth. ‘The first three joints are 
sub-equal, and the fifth and last are about equal in length to that of the 
first three, but are narrower ; while the fourth and seventh are smaller 
than those that preceed or follow. The inner branches of the third pair 
in the male are provided with an elongate spiniform appendage, slightly 
hooked at the end (fig. 22). The basal joint of the fifth pair is furnished 
with only two small spiniform sete. The secondary branch is somewhat 
like that of the female, but rather smaller. 
Habitat.—At Seafield, near Leith, among mud near low-water mark. 
This species resembles Thalestris forficula, Claus, but differs in several im- 
portant particulars,—it differs in the proportional lengths of the joints of 
nine-jointed anterior antenne ; it also differs in the structure of the swim- 
ming-feet, as shown by the description and figures. 
Genus Pseudowestwoodia, nov. gen. 
Very like Westwoodia in general appearance when seen from the side. 
Anterior antennee six or seven-jointed. Secondary branch of posterior an- 
tennze small, one-jointed. Mouth appendages similar to those of West- 
woodia. Both branches of first pair of swimming-feet two-jointed, but in 
general appearance the first pair resemble those of Westwoodia. he other 
thoracic appendages are similar in structure to those of that genus. The 
distinctive characters of Psewdowestwoodia are the one-jointed secondary 
branch of the posterior antenne, and the first pair of swimming-feet with 
both branches two-jointed. All the other characters are more or less 
similar to those of Westwoodva, hence the proposed generic name for the. 
form now under consideration. 
Considering the many points of resemblance between the characters of 
the species now to be described and those of the genus Westwoodia, a 
