REPORT ON THE OIRRIPEDIA. 153 



of longitudinal striae; the longitudinal furrow is absent or has Iwcome ili.nl |.y tin- sides 

 being folded inwards. The apex is slightly beaked, the scutal margin is distinctly con- 

 cave. The spur is broad and blunt, placed at less than its own width from the basi 

 scutal angle; the hinder side of the spur slopes into that part of the basal margin of 

 the valve which is situated behind the spur. A very distinct articular ridge runs from 

 the apex half way along the valve. The crests for the depressor muscles are hardly 

 visible. 



With regard to the structure of the body of the animal, the following details may 

 rind a place here. 



The mouth has a labrurn with a deep notch, and with three or four extremely small 

 teeth on each side of the notch. The palpi are large, densely covered with not very 

 long hairs. The mandibles have five short and blunt teeth, the undermost two of 

 which are rudimentary. The maxillcv (PI. XIII. fig. 22) have the edge straight, with a 

 very small rounded notch behind the two greater spines; at a little distance from the 

 inferior angle there is another large and broad spine, and, moreover, a considerable number 

 of smaller spines between the larger ones. The second maxillce are elongate, densely 

 clothed with hairs on their anterior surface. The first pair of cirri has very unequal 

 rami ; the shortest has ten, the longest and anterior ramus has twenty segments. The 

 shorter ramus has the segments very protuberant in front, and thickly clothed with 

 spines, which are placed in tufts on the front and the hinder margins of each segment. 

 The other cirri did not show anything very particular. 



A group of about ten specimens is attached to a stone ; two other specimens arc 

 attached to a branch, &c. The size of the specimens is slightly different ; the largest 

 specimen has a height of not quite 9 mm., and the greatest diameter of the base is 7 mm. 



This species was taken together with specimens of Balanus trigonus, and with 

 Balanus amaryllis, at Station 233a, May 17 to 19, 1875; lat. 34° 85' N., long. 135° 

 10' E. : depth, 8 and 50 fathoms; bottom mud, sand. Kobe, Japan. 



Section F. Parietes and radii not permeated by pores; basis sometimes permeated by 

 pores, sometimes not, and sometimes excessively thin and hardly distinguishable. 



Balanus amaryllis, Darwin (PL VII. figs. 4, 5). 



Balanus amaryllis, Darwin, Balanidse, 1854, \\ 279. 



This is, according to Darwin, a distinct and well-defined specie-. It is characterised 

 by the walls and radii not being permeated by poroes; by its porous basis, by the 

 extremely narrow radii, with their quite smooth, rounded, and very oblique summits. 

 Its scutum is striated longitudinally, its termini has a very narrow spur. II.. M.S. 

 Challenger took specimens of this species on two occasions; once near Station 186. in 



(ZOOL. OHALL. EXP. — PART XXV. — 1883.) Bb 20 



