MALE. 249 



side were smaller than the two on the other side, — the 

 smaller beads being ^iio, and the larger, suo of an inch 

 in diameter ; therefore more than twice the size of one of 

 the beads in S. vtdgare, which are only WV o externally in 

 diameter. From the position of the eye, close to one 

 margin, near the upper end of the flattened animal, and 

 from the manner in which the little limbs and spines 

 lay between two of the beads at the opposite end, it was 

 manifest that these latter, one large and one small, cor- 

 responded with the terga of the other cirripedes, and that 

 the other two, near the eye, answered to the scuta. The 

 valves being of unequal sizes on the right and left-hand 

 sides of the animal, is probably connected with one side 

 being pressed against the hard, shelly valve of the female ; 

 in the same way as the valves in certain Psecilasmas, 

 are smaller and flatter on the side nearest to the crus- 

 tacean to which they are attached. The eye, in being 

 slightly notched on the upper and lower edge, shows 

 signs of really consisting of two eyes, which I believe is 

 always normally the case ; it is rather larger, in the pro- 

 portion of 13 to 1 1, being tjMW of an inch in diameter, 

 than in S. vulgar e; and from the almost perfect trans- 

 parency of the integuments, is far more conspicuous than 

 in that species. Hence when the valves of the female are 

 opened, the black little eye is the first part of the male 

 which catches the attention. No vestige of a mouth could 

 be discovered. 



Thorax and Abdomen. — The thorax, as in S. vulgare, 

 is highly extensible, and when stretched exhibits the 

 same five transverse folds or articulations; when con- 

 tracted, it is broader, so that even the truncated end of the 

 abdomen is wider than the lower (properly anterior) end 

 of the thorax in S. vidgare. Its thin outer integument 

 is studded with excessively minute points in transverse 

 rows. The four pair of limbs are longer than in S. vidgare ■, 

 but the spines on them much shorter and thicker ; each 

 limb (including the first) supports three spines, of which 

 one is seated on a notch low down on the outside, and 



