ccxxxvm 
APPENDIX. 
The middle lamella of the tail has seven spines on each side in the spe- 
cimen vs^hich has been figured ; but others had a greater or less proportion : 
the exterior antennae are verrucose on the inner side. 
Alpheus Polaris. 
Thoracis dimidio posteriore Icevi, anteriore carinato serrate ; chelis et unguibus apice nigris. 
Plate II. fig. 5 — 8. 
Fig. 8 is the rostrum of a second specimen. 
Several individuals were brought up in the same drag-net, from fifty fathoms’ 
depth, on the coast of Melville Island, all of which agreed in the pecu- 
liarities included in the specific character, but no two in the number 
of the teeth or in the shape of the rostrum, the former varying from three 
to six above, and from two to six below ; length usually from one and a 
half to three quarters of an inch ; colour pale, with red spots and mark- 
ings ; thorax armed on each side on the anterior margin with three 
spines, situated above and below the eye and at the junction of the lateral 
margin ; these spines vary in strength in different individuals, the first espe- 
cially being occasionally very strong : anterior half of the thorax carinate 
on the back, and serrate ; posterior half smooth, without carina or teeth ; 
the upper seta of the superior antennsB hollowed beneath, ciliate at the sides ; 
both pairs spinous at the joints ; pedipalpi, three-articulate, the last joint 
above three times the length of the second, much depressed, hirsute, and ter- 
minated by from four to six stiff black bristles ; the fingers of the four anterior 
legs and the nails of the others black at the points ; the nails are spinulose 
within ; the first pair of swimmers smaller than the others, bifid and pointed ; 
the hinder part of the third segment of the body is curved towards the tail, 
and the lateral lobes of the two next segments are produced in sharp points 
directed backwards ; tail with two strong spines at the last joint ; the 
middle lamella with ten spines above, five on each side ; terminated by two 
strong black bristles. 
