Barnacles of the Genua Scalpellura. 1 I I 



half as great again as its width, the 1 I valves covered with 

 opaque cuticle:, only the umbones exposed (fig. 3, A ), the 

 surface with a very short velvety pile; on removing the 

 cuticle the valves are seen to be separated by rather wide 

 chitinous interspaces (fig. 3, B). Tergum quadrilateral, with 

 nearly Btraight sides, about twice as long as wide, with 

 rather widely spaced and not very prominent lines of 

 -ih. and with a faint ridge running from the apex to the 

 basal angle; the straight occludent margin forms a slight 

 angle with that of the scutum. Scutum triangular, with the 

 inner margin obtusely angled about its middle, so that the 

 valve becomes almost quadrilateral, about twice as high as it 

 is wide, apex very slightly recurved, occludent margin slightly 

 convex. Carina simply bowed, nearly straight in its lower 

 half, umbo apical, touching but not entering between the 

 terga, lower end rounded, more or less widely separated from 

 carina] latera (tig. 3, J>) ; roof strongly convex, not defined 

 from the parietes. Upper latus triangular, with umbo at the 

 acute scuto-tergal angle, basal and tergal margins convex, 

 scutal margin concave. Rostral latent (fig. 3, C) very low, 

 apices incurved, separated by the minute rostrum. Infra- 

 median tutus small, triangular, about as high as it is wide at 

 the base. Carinal tutus much wider than high, not projecting 

 behind the carina, umbo at upper end, a more or less distinct 

 ridge exteuding from umbo to inner angle. The two carinal 

 latera do not meet behind (fig. .'j, D). 



Peduncle short, with large [dates, not imbricated, arranged 

 in six longitudinal lows of about five plates each. Free 

 margins of plates rounded except in the carinal scries, where 

 they are bluntly angled. 



Mandible ( fig. 3, Ej with four teeth (including inner angle), 

 the interval between the two distal twice that between the 

 second and third. Cirri purplish or greenish. First cirrus 

 with rami of about 9 and 14 segments. Sixth cirrus with 

 rami of about 30 segments which about the middle bear 

 three pairs of long spines anteriorly with a few finer sctie 

 between. Caudal appendages (fig. 3, F) in holotype less than 

 twice as long as peduncle of sixth cirrus., with 13 segments, 

 in paratype more than twice as long as peduncle and with 

 25 segments. Penis about as long as caudal appendages, 

 tapering, without conspicuous set. 



Measurements. — Length of capitulum 20 mm., breadth 

 12*5 mm. : length of peduncle 11 mm., diameter 7 mm. 



Remarks. — This species belongs to the group Arco. 

 BCalpellum, and by its wide carinal latera with the umbo 



