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Volume 19, 1886
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– 194 –

Art. XXV.—On a New Species of Alpheus.

[Read before the Wellington Philosophical Society, 18th February, 1887.]

Plate VId.
Alpheus Halesii.

Carapace smooth, long, somewhat compressed, one and a half times as long as broad, the portions over the eyes very prominently arched; rostrum small, extending back beyond the base of the eye arch; total length one-fourth that of carapace.

Internal antennœ, second joint twice the length of the first; the basal scale terminates in an acute point.

External antennœ, basal scale stout, larger than the peduncle, very thick on outer edge, curved outwards, terminating in sharp point.

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Large hand, sometimes right, sometimes left; three-fourths the length of the animal (from tip of rostrum to end of telson); quadrate, superior inner angle keeled, with a line of hairs on the anterior two-thirds of the length; outer angle also keeled, but not so prominently, no hairs. A very pronounced keel runs down the centre of the back (outer face) of hand, terminating in a swelling at the insertion of the mobile finger. Inferior outer angle keeled but hairless, keel does not reach to the base of the immobile finger. Inferior inner angle not keeled, but with a row of stout hairs running the whole length, and continued on to the immobile finger, a line of minute tubercles at the base of these hairs.

Immobile finger stout, with strong and curved claw, rather swollen in the middle, with five or six bristles at equal distances along the outer margin, but inside the line of hairs mentioned as running along the inferior margin of hand. On the inner margin of this finger, and about the centre, is a deep oval pit, on the posterior margin of which is a bunch of stout hairs. A pair of stout hairs placed just at the curve of the claw.

Mobile finger stout, compressed, with a large oval tubercle corresponding with and fitting into the pit on the immobile finger; upper edge sharp, a line of hairs along the margin; closes well within the curved hook of the other finger.

Wrist short, swollen, anterior edge sharp but not toothed; a short stout spine, directed backwards, at the inner and outer posterior margins.

Arm triangular; superior angle with a stout spine directed forwards, situate one-fourth of the distance from the anterior margin, with a few stout hairs in front and behind. Internal margin terminates anteriorly in a spine, with a tubercle close above its base; four stout spines placed at equal distances along the margin behind, the spines being flanked by a line of hairs; external margin sharp and very finely serrated along the entire length.

Smaller hand, fingers long, curved, hairy, meeting at the tips, but not touching at any other part of their margins. Wrist of second pair of legs with first joint longest. Terminal joint of other legs flattened for swimming and shaped like a spear-head.

Size of largest Specimen.
Inches.
From tip of rostrum to end of telson 1 7/20
Length of carapace 9/20
Greatest width of carapace 5/20
Length of largest hand (inclusive of fingers) 1.0
Width " 5/20
Thickness " 3/20
Length of immobile finger 4/20
" mobile " 3/20
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Locality: East Coast of Wellington Province.

This species approaches A. rubrum, from Europe. It is named in honour of Mr. Hales, on the coast of whose sheeprun it was obtained.

Description of Plate Vid.

Fig. 1 Animal, showing inside of large hand.

Fig. 1 Back of large hand, showing keel, etc.