158 THE VOYAGE OF H.M.S. CHALLENGER. 



is wanting in the present species. The outer maxilla' have the ordinary shape, their 

 inner faces being rather indistinctly divided into two lobes. 



Cirri. — The rami of the first pair are only very slightly unequal ; both have fourteen 

 segments, but the anterior ramus is slightly longer, because the segments themselves are 

 a little linger. The breadth of the two rami is nearly equal; the anterior surface of 

 each segment is produced in both rami; the projections bear a tuft of spines on their 

 summit. The rami of the second pair are unequal as far as the number of segments is 

 concerned : this is seventeen in the shortest, and twenty-three in the longest ramus. 

 The segments, and especially the lower ones, are produced ; the projections thus formed 

 are crowned by a tuft of spines. The rami of the third cirrus have respectively 

 twenty-five and twenty-eight segments. The lower segments are produced on 

 their anterior surface. The three anterior pairs are much shorter than the three 

 posterior ones; whereas the former three are straight or only slightly bowed, the 

 latter are distinctly curled. The number of the segments is much more considerable, 

 and is in the fourth pair thirty-two and Thirty-seven. The number of spines on each 

 segment is two, three, or four pairs, two on the upper, three on the middle, four on 

 the lower segments, small spines being inserted between the larger ones in a not very 

 regular way. The undermost part of the pedicels of the four anterior cirri is much 

 swollen, and projects as a kind of vesicle beyond the surface of the animal's body. 



The penis is long and only indistinctly hairy; but, whilst it is rather thick near the. 

 under extremity, it grows very slender at the other end. 



This species lives attached to pebbles and also to the spines of a Cidaris. The latter 

 specimens are a great deal smaller than those which were found attached to pebbles. 

 Six specimens were taken, only two of which were of considerable size. Scalpellum 

 recurvirostrum, n. sp., was procured with the same haul of the dredge. This was at 

 Station 150, February 2, 1874; lat. 52° 4' S., long. 71° 2-2' E. ; depth, 150 fathoms, 

 bottom temperature, 1 0, 8 C. ; bottom, rock. 



For the differences between this and next species, vide under the same. 



Balanus hirsutus, n. sp. (PL XIII. figs. 8-15). 



Basis membranous; radii absent; parietes not permeated by pores; articular ridge 

 of the tergum broad, but not extending solar downwards as in Balanus corottiformis. 

 Carinal margin of the tergum much shorter than the basal margin. Membrane lining 

 the growth-ridges with distinct spines. 



Balanus hirsutus and Balanus corottiformis are two nearly related species, corre- 

 sponding in all essential respects. I must consider them, however, as different species, 

 because their shape is quite different, and in the second place, because the tergum 

 shows very striking differences also. 



