188 1BLA CUMINGII, 



of the cirri. The first cirrus is rather short, with the rami 

 unequal in length by about two segments : the anterior 

 ramus is shorter and thicker than the other : segments 

 numerous, each clothed with several rows of bristles. 

 The second cirrus has the anterior ramus thicker and 

 more thickly clothed with spines than the posterior ramus ; 

 this latter is rather more thickly clothed with spines 

 than are the three posterior cirri : the third cirrus is in 

 all these respects characterised like the second cirrus, 

 but in a lesser degree. The pedicels of the second and 

 third cirri are thickly and irregularly clothed with spines ; 

 in the three posterior pairs, the spines are placed in two 

 regular rows, with some minute intermediate spines. 



Caudal Appendages (PL IV, fig. 8 a',/), multiarticulate, 

 thin, tapering, in one specimen equalling, in another just 

 exceeding, in length the pedicels of the sixth cirrus. In the 

 latter specimen there were thirteen segments, of which the 

 basal segments were broader and shorter than the upper ; 

 these latter are slightly constricted round the middle, so 

 that they resemble, in a small degree, an hour-glass. 

 Their upper margins are surrounded by rings of bristles ; 

 the terminal segment being surmounted by one or two 

 very fine bristles much longer than the others. The two 

 appendages are closely approximate ; each arises from a 

 narrow elongated slip, attached to the side of the pedicel 

 of the sixth cirrus. 



Nervous system. — I examined the upper part of the 

 nervous chord, in order to ascertain whether the infra- 

 cesophagean ganglion, which is of a globulo-oblong shape, 

 was far separated from the second ganglion ; and this I 

 found to be the case, in accordance with the distance of 

 the first cirrus from the second. I may here remark, that 

 in S. quadrivalvis I discovered the eye, which, though in 

 all probability really double, appeared to be single ; it was 

 situated near to the supra-cesophageal ganglion ; and this 

 ganglion was situated near to the adductor scutorum 

 muscle, and at a considerable distance from the labrum. 

 The aperture leading into the acoustic (?) sack, is situated 



