254 
- 30+19+14-10'°5-8- 
ee ern ares Ons 
80, 19S 10> 142 3° e7= 
+ Posterior antennse ae moderate length, three-jointed ; joints nearly 
a equal, a small one- (? or two-) jointed secondary branch springs from the 
. end of the first joint, and bears three subequal terminal hairs ; two of these 
hairs arise from a common and somewhat dilated basal part which may 
possibly represent a rudimentary second joint, but this is doubtful. 
Mandibles moderately stout, the biting part broad with several strong 
tooth-like processes, and a divergent, marginal, setiferous spine; the palp 
with two small branches and one or two terminal hairs. Maxillz small ; 
the terminal part, which is comparatively broad, is furnished with sever al 
spiniform teeth on the inner distal margin, and exteriorly- with three 
small marginal setiferous lobes. Anterior foot-jaw small, two-jointed; the 
first joint with two marginal setiferous lobes, the last joint small and 
produced into an elongate slender process, bearing at its apex a stout 
plumose hair, and exteriorly, near the base, a-plain slender seta. Posterior 
foot-jaw strong, and armed with a powerful clawed spine. The first four 
pairs. of. swimming feet have both branches three-jomted and elongate; 
the first joint of the ner’ branch of the first pair longer than the entire 
. outer branch, and furnished with: an elongate seta on the lower half of 
the inner margin; the two last joints are short, the second being the 
shorter of the two. Inner branches of each of the other three pairs 
shorter than the outer,—especially in those of the fourth pair; all the 
four pairs furnished with moderately long plumose sete. ‘The inner part 
of the basal joint of the female fifth pair moderately broad, furnished 
with four elongate sect on its inner margin; the outer part is laterally 
- produced and attenuated, and forms the base of a single elongate seta. 
‘The second joint is long and slender (fig. 12), and furnished with five 
setae,—three on the outer margin, one on the inner margin near the apex, 
and an apical seta. The fifth | pair in the male are very small; the basal 
"joint is scarcely produced posteriorly, and bears three subterminal setae 
the lateral produced part. bears a single hair, the second joint narrow, 
ciliate on the outer margin, and furnished with one terminal seta, and 
another on the inner margin, both being of moderate length. The first 
abdominal segment bears two small setiferous lateral appendages, as 
shown in fig. 16. Caudal stylets elongate, slender, longer than the last 
abdominal segment, each with one ‘extremely long and a few short 
terminal sete. The posterior margins of all the cephalo- -thoracie and 
abdominal segments are more or less distinctly denticulate. 
A variety occurs, somewhat smaller than that described (figs. 17, 18), 
- which has the antero-lateral angles of the first body segment rounded instead 
of angular; the posterior margins of all the body segments spiniferous 
instead of denticulate, and also armed at the postero-lateral angles with 
two: strong spines and several small set. To distinguish this variety I 
have named it var. spinosa. | = 
_ Habitut.—Off St Monans, Firth of Forth. Frequent. I first obtained 
this species two or three years ago, but for want of time to study its 
structure and affinities, it was laid aside, along with some others, till a more 
convenient season. With the assistance of my son, I am now able to 
describe this and several other interesting members of the Forth fauna. 
- Paramesochra,* nov. gen. (provisional name). 
Body subpyriform ; anterior antenna short, seven-jointed in the female ; 
* Near Mesochra, Boeck, which it resembles in several important points, eapeell 
in the structure of the first g pairs of swimming feet. 
