238 Mr. Lubbock on the 



in certain other Calanidce. The liairs are chiefly simple or lan- 

 ceolate. 



The total length of the organ is -^-^ of an inch. 



The second pair of antennae are very like those of D. Castor. 

 The hairs do not appear to me to be plumose ; they are much 

 longer than represented in Dr. Baird's Plate XXVI. fig. la, being 

 as long as the organ itself. The second segment bears a row of 

 small bristles, which occurs in all the allied species which I have 

 examined. The palpus is 7-jointed, and the second segment, count- 

 ing from the base, appears to consist of three, which have partially 

 coalesced. Each segment bears a long simple hair, and the apical 

 segment has three. 



The mandibles are very like those of the European species, and 

 both have eight teeth, but in the present the interior, as well as 

 the exterior tooth, is larger than the others. The palpus is much 

 thicker, and the hairs longer, in proportion, than in Dr. Baird's 

 figure. 



The second pair of maxillcc are very like those of D. Castor. 

 They are indistinctly 3-jointed, and bear about twenty hairs. 



Length .,^iy. 



The third pair of maxillipeds are 7-jointed ; the two basal seg- 

 ments are the largest, and bear respectively two or three small 

 hairs. The terminal portion is smaller than in D. Castor, especially 

 the last two segments, which have almost coalesced. 



Length 3J0. 



The thoracic legs are very similar to those of D. Castor. 'I'he 

 two branches are both 3-jointed. The hairs are arranged as 

 follows. Beginning with the external and larger branch (fig. 5), 

 the two basal segments have each two hairs at the apex, one at 

 each side. The apical segment has eight ; the three which are 

 situated on the outside are short, stout and spine-like, while those 

 on the inner side are long, slender and plumose. They evidently 

 assist in swimming. 



The smaller branch has one hair at the apex of the basal joint, 

 two on the second and six on the apical joint, all on the inner 

 side, and similar to those of the other branch. The large basal 

 segment has, as usual, a plumose hair on the inner side, and the 

 second, from which the two branches spring, has two hairs, one of 

 which is lanceolate. 



The basal segment appears to contain three muscles, two 

 flexors and an extensor. The first flexor appears to move the 

 plumose hair, and I am not sure that the other two are not con- 



