250 
Part III.— Tenth Annual Report 
Tachidius crassicornis, n. sp. (provisional name). (PI. VIII. figs. 14-27). 
Length, exclusive of tail setae, '7 mm. Body moderately stout, first 
cephalo-thoracic segment longer than the next two together, the forehead 
produced into a short rostrum. Anterior antennae shorter than the first 
body segment ; that of the female six-jointed, stout, and densely' setiferous 
towards the extremity, a small sensory filament springs from fifth joint. 
The proportional length of the joints are nearly as in the formula 
20 • 10 • 9 • 5 • 3 • 9 
1 • 2 • 3 • 4 • 5 • 6 ' 
The anterior antennae in the male form powerful grasping organs, closely 
resembling those of Tachidius brevicomis (fig. 17). Posterior antennae 
short, three-jointed, the last joint nearly aslong asthe preceding two together ; 
a small one-jointed secondary branch springs from the end of the first 
joint. Mouth organs nearly as in Tachidius brevicomis. The first four 
pairs of swimming feet nearly alike, both branches three-jointed, the first 
joint of the inner branches of all the four pairs smaller than either the 
second or third joints. The fifth pair in the female moderately large 
and foliaceous, furnished with three equal and plumose terminal seta ; a 
plumose seta springs from a rounded basal part on the anterior margin of 
the female fifth pair, which may represent a rudimentary second branch. 
The fifth pair in the male are very small, subquadrate, and furnished with 
one small and two moderately long setae near the inner angle and one at 
the outer angle ; the first abdominal segment in the male is armed with 
prominent lateral appendages, which are easily observed without dissection, 
and which consist of a broad, but short, basal part bearing three unequal 
spiniform and plumose marginal setae, the inner one being longer than 
either of the other two. Caudal stylets short, about as long as the last 
abdominal segment, and furnished with four setae, — the inner and outer 
being plain aud very small, the other two plumose and elongate ; the inner 
of the two principal setae is much longer than the other ; and the basal 
part of the proximal half is broader than the remaining portion ; the broad 
part, which is of nearly equal breadth throughout, merges abruptly into 
the more slender portion as shown in the figure. Ovisac single, large, 
with a number of large ova. 
Habitat. — 'Near Culross on the upper estuary of the Forth ; not very 
rare. Obtained February 1892. 
This species comes near Tachidius brevicomis (Miiller), but differs in 
the form of the anterior antennae, which are rather stouter and shorter 
and six-jointed ; in the first joint of the inner branches of the first four 
pairs of swimming feet being smaller than the other two joints ; and in 
the form of the fifth feet in the female. 
Ameira longicaudata* n. sp. (provisional name). (PI. IX. figs. 1-18). 
Body slender ; length, exclusive of tail setae, 1 mm. (25th of an inch). 
Anterior margin of first body segment squarely truncate; forehead produced 
into a short blunt rostrum. Anterior antennae longer than the first 
cephalo-thoracic segment, elongate, and sparingly setiferous ; that of the 
female eight-jointed, of the male nine-jointed ; the male antennae are 
distinctly hinged between the sixth and seventh joints, and indistinctly 
between the third and fourth joints. A long sensory filament springs from 
the end of the fourth joint in both sexes ; the porportional length of the 
joints of the female and male antennae are nearly as in the annexed 
formulae 
* Referring to the long caudal stylets. 
m 
