Entomostraca from the Scottish Seas. 123 



gathering of Crustacea from 1140 metres, collected by tlie 



' GolJseeker ' at Station 53, about 70 or 80 miles north by 



west of the Butt of Lewis {6.f 36' N. hit,, l"" W. long.). 



As tiiis specimen represents what may be either an un- 



described species or the undescribed male of some species the 



female of which is already known, the following particulars 



concerning it may not be without interest. 



The specimen has a general resemblance to Xanthocalanus 



horeall<i, G. 0. Sars, and measures about 2*5 mm. in length 



(H^. 1). _ _ 



Rostrum of moderate size and bifurcate, the segments are 



elongate, stout at the base, but taper towards the pointed 



extremities (fig. 1 a). 



Antennules wanting ; the antennse, which are also slightly 



imperfect, resemble those of JT. borealis (fig. 2). 



Mandibles stout, with a strong masticatory part ; the tooth 

 on the inner aspect of the biting-edge is broad and massive 

 and projects soraewliat beyond the others (fig. 3) ; the 



mandible-palp, which is stout, is slightly imperfect (fig. 4). 



First maxillipeds stout, each of them armed with two or 

 three long and stout setiferous spines and a number of elon- 

 gated plumose bristles, and there is also present the charac- 

 teristic fascicle of sensory filaments (fig. 5). 



The four pairs of swimming-feet were all more or less 

 imperfect : fig. 6 represents what remains of the fourth pair. 

 The fifth pair has the left leg greatly elongated and slender, 

 so that it is only a little shorter than the entire length of the 

 cephalothorax. The basal joint of this leg is moderately 

 stout and rather longer than the right leg ; the next three 

 joints are subequal and considerably longer tlian the basal 

 joint, and each is more slender than the joint that precedes 

 it ; the end joint is very small and terminates in a bifurcated 

 process, as shown in the enlarged figure (fig. 7 a). The rio-ht 

 leg is short and rudimentary, and appears to be composed of 

 three (or four) joints (fig. 7). 



Remarks. — This species appears to be a true Xanthocalanus. 

 The structure of the antenna3, and especially of the first 

 maxillipeds and of the fifth pair of thoracic legs, agrees with 

 the characters common to the species of this genus. The 

 first maxillipeds are each furnished with a terminal fascicle 

 of slender sensory filaments as in X. horealis, but with no 

 sheaf-like bundles as in AmaUophora; they are also armed 

 with two strong, elongated, and more or less setiferous spines, 

 besides a number of plumose setae. Further, in the fifth 

 pair of thoracic feet the right leg is very short, while the left 

 is slender and elongated as in X. borealis. In the species 



