106 BULLETIN 60, UNITED STATES NATIONAL MUSEUM. 



The penis (Plate V, Ho-. 6) is stout and short, with only weak annu- 

 lation, chiefl}' in the median portion, and it is clothed with rather long- 

 delicate hairs, which seem to be irregularly placed. 



The imperfectly calcified scuta are shaped much like those of Con- 

 choderiiiu vlrgatum var. hunteri, but with an additional diverging' lobe 

 or ray below. Owing to the absence of definite outlines, the shape of 

 the plate is not clearly to be seen. 



The t^'pe is a large individual, with a 3'oung one adhering at the base 

 of the capitulum. Several other smaller examples were taken with it. 

 ^1. pacijica is a much larger form than A. pellucida (Aurivillius) of 

 the Atlantic. The integument is also less transparent. The arrange- 

 ment of the teeth of the mandible is different, those of A. pacijica 

 being more equally spaced, without a wider space below the upper 

 spine. The maxilhe also are unlike in the Atlantic and Pacific species, 

 that of A. pacijica being remarkable for the very short spines and 

 the ver}^ irregular edge. 



A. pacijica must be compared with A. univalvis (Quoy and Gaimard) 

 of the eastern Atlantic. That form is at present known onh' by very 

 inadequate descriptions and figures, and its exact structure remains to 

 be investigated. From existing data it seems to be very similar to 

 the Pacific form; yet the specific identity of forms so widely separated 

 geographically could not prudentl}' be affirmed without a comparison 

 with Atlantic material. The essentially pelagic hal)it of the genus leads 

 us to anticipate wide dispersion of the species, limited only by the dis- 

 tribution of the large medusfe which serve as their hosts. (Fig. 36.) 



Family VERKUCID JC Darwin. 



Sessile, box-like, asymmetrical barnacles, in which the wall is com- 

 posed of the rostrum, carina, a scutum, and a tergum, immovably 

 interlocked, and all much specialized in shape; the other scutum and 

 tergum are movable, forming the lid-like top. Caudal appendages 

 are very long, composed of numerous segments. 



This very distinct family consists at present of a single genus. 



Genus VERRUCA Schumacher. 



1817. Verruca Schumacher, Essai d'uii nouv. syst. Vers Testaces, p. 91. 

 1851. Darwin, Monograph on the Cirripedia, Balanidse, p. 496. 



Doctor Hoek, in describing the deep-water species obtained b}" the 

 Challenger, has commented upon the similaritv of the several forms, 

 and expressed grave doubts as to their specific value. Individuals are 

 much rarer than in Scalpellum or Poecilasma^ most of the forms being 

 known by only one, or at best b}" ver}' few examples, so that we have 

 little opportunity to ascertain the ordinary range of individual varia- 

 tion. The characters of sculpture upon which the species are largel}- 



