138 GENUS CONCHODERMA. 



of the valves (together with the primordial valves) are nearly 

 central, so that they are added to at their upper and lower 

 ends ; hence their manner of growth is considerably dif- 

 erent from that of the valves in Lepas. The adductor 

 muscle is attached to a slight concavity on the under side 

 of each scutum, at the point whence the lobes diverge. 



The Terga are placed almost transversely to the scuta ; 

 at their lower ends, there is either a very slight prominence 

 in the capitulum, or there is a large tubular, folded ap- 

 pendage, opening into the sack, and apparently serving 

 for respiratory purposes. 



Peduncle, smooth, moderately long; attachment effected 

 by the cement-stuff being poured out exclusively, as it 

 appears, from the larval antennae. These antennae in 

 C. aurita and C. virgata, resemble, in the form of the 

 disc and in the long feathered spines on the ultimate seg- 

 ment, those in Lepas. 



The Filamentary Appendages are highly developed; 

 there are six or seven on each side ; two are attached 

 beneath the basal articulation of the first cirrus (as is usual 

 in Lepas), and near them there are one or two small 

 pap-formed projections of apparently similar nature ; the 

 rest of the filaments are attached to the posterior edges 

 low down, on the lower segments of the pedicels of the 

 cirri. I believe, in all cases, these appendages are occu- 

 pied by testes. 



Prosoma, moderately developed. 



Mouth, situated not far from the adductor muscle ; 

 labrum considerably bullate, with the crest hairy and 

 pectinated with inwardly pointing, approximate, flattened 

 teeth : inner fold of the supra-cesophageal cavity slightly 

 thickened and yellowish, villose on the sides. 



Palpi of the usual shape, not meeting, moderately 

 broad. 



Mandibles, with five teeth, graduated in size, nearly 

 equidistant, finely pectinated either on one or both sides 

 towards their bases; inferior angle narrow, either pro* 

 duced into a fine tooth, or almost rudimentary. 



