REPORT ON THE CIRRIPEDJA. I.">7 



Eehinid, and these have very narrow Kascs; the larger specimens, however, havi 

 circular base, and are found attache,! to stones. The base is very thin, membranous. 



The opercular valves are unite, 1 together, and to the she'll by strong membrane of a light 

 yellowish colour. The exterior surface of the valves is totally hidden by a thick hairy 

 chitinous membrane. The shape of the scutum (PL XIII. figs. 2 and 3) is very peculiar. 

 The growth -ridges are very broad and distinct in the superior half of the valve, they are 

 very narrow and only slightly developed in the interior half. The valve is distinctly 

 bowed, so that the outer side is concave. The occludent margin is slightly inflected, the 

 basal margin is convex, the tergal margin describes a bow. Internally the articular ridge 

 is well-developed, and there is also a pit marked by a slight ridge for the reception of the 

 lateral depressor muscle. The occludent margin is internally strengthened by a well- 

 developed ridge, which rims along the whole margin, but which is especially developed near 

 the basal margin. The cavity for the adductor muscle is hardly visible. The tergum 

 (PL XIII. tigs. 1 and 4) is also slightly bowed, hence concave at the outer side. The apex 

 is pointed and almost imperceptibly beaked. Its scutal margin is long and straight; it 

 is separated by a narrow ridge from the shallow furrow, which runs almost from the apex 

 down to the extremity of the spur. The occludent margin is convex, and only little 

 shorter than the nearly straight basal margin. The spur is not very distinct, and runs 

 almost to the basi-scutal angle of the valve. Internally the valve is well marked by the 

 very strong development of its articular ridge, which from the apex extends almosl I 

 the middle of the scutal margin, and which, when seen from the exterior side, projects 

 very considerably beyond the scutal margin of the valve. The crests for the depressors 

 are not very prominent. 



The size of the largest specimen is 45 mm. from the tip of the opercular valves to 

 the base. The distance between the apices of the rostrum and carina is about 2'.t mm. 

 The greatest diameter of the base is 16 mm. 



The structure of the month is in many respects very remarkable. The edge of the 

 labrum (PI. XIII. fig. 5) is not furnished with teeth, but is bordered by extremely minute 

 hairs. What is much more interesting is that it is not notched at all, whereas Darwin 

 says that it is always notched in this genus. The palpi are robust and very long, with 

 their apices almost touching each other. Their surface is furnished with very numerous 

 curled spines, which are not smooth, but in their turn are furnished with very small hairs. 

 The mandibles (fig. 6) have four teeth, and the inferior angle is divided into three very 

 small teeth, the first of which is laterally bordered by some extremely small teeth. The 

 distance between the first two teeth of the mandible is greater than that between 

 the following ones. The muxllhe (fig. 7) show a small quadrilateral notch behind the 

 two larger upper spines ; the part below the notch is slightly projecting, and is furnished 

 with numerous densely crowded spines of nearly the same size. The pair of lower spines 

 larger than the others, which is present on the maxilla of most other species of Bnl<i,,n.-< t 



