92 EULLETTX 03, UNITED STATES NATIONAL MItREUM. 



knov/n form of B. ampldtrite is in tlie slightest degree ribbed. It may 

 prove to be closely related to, or specifically identical with, B. vio- 

 laceus Gnivel, described from specimens in the British Museum, the 

 locality unknown; but that form, from the description and figures, 

 differs from albicostatus by several minor details of the internal 

 structure of the scuta, and particularly by the terga, which "pre- 

 sentent exterieurement une serie de plissements longitudinaux plus 

 ou moins profonds" — a stinictiu'e quite absent in B. a. albicostatus. 

 In my opinion, B. violaceus would be better as a subspecies of B. 

 ampMtrite than as a distinct species. The name is preoccupied by 

 Graelin, his Lepas violacea being a Balanus. 



Wliether Balanus miralilis Kriiger is an old specimen of allncos- 

 tatus can not now be determined, since its hard parts are so exten- 

 sively eroded that specific characters are largely obliterated, and 

 the cirri and other internal parts were destroyed. There is no evi- 

 dence that it was ribbed. .The characters of B. wirahilis, so far as 

 made out, are those of B. ampldtrite; but it may have had other 

 features, now lost by corrosion. Until difrercntial features are shown 

 to exist, B. mirahilis may well be considcn^ed a synonym of B. am- 

 pliitrite 



BALANUS AMPHITRITE NIVEUS Darwin. 



Plate 19, figs. 1 to 2e. 



1854. B. a., var. niveus Darwin, Monograph, p. 240, pi. 5, fig. 2/ 

 1867. Balanus improvisus, var. assimilis Darwin, and bastard, B. armafus and 

 B. improvisus, var. assiviilis, Fritz Muller, Arcliiv fiir Naturgeschichte, 

 Jahrg. 33, vol. 1, pp. 329-356, pi. 7, figs. 22, 29-43; pi. S, figs. 45, 49-51. 

 1912. Balanus crenaius Bruguiere, Fowler, Crustacea of New Jersey, in Ann. 

 I?ep. N. J. State Mus. for 1911, pi. 46 (Cape May, N. J.). 



Distribution. — Vineyard Sound, Massachusetts, to the Gulf of Mex- 

 ico; Southern Brazil. Low water to about 30 fathoms.' 



"White, with longitudinal hyaline lines; epidermis not persist- 

 ent." Radii rather wide, with oblique, somewhat irregular summits. 

 Parietes smooth, ribbed inside, but slightly hollowed behind the 

 sheath; the parietal tubes having transverse septa in the upper part, 

 open below. Basis thin, porous, except in the center. 



Diameter 10 to 12 mm., often smaller. 



Scutum finely ridged externally. Articular ridge somewhat re- 

 flexed, more than half the length of the tergal margin, continued 

 downward in a ridge bounding the lateral depressor muscle pit. 

 Adductor ridge strong, but short. 



Tergum level or with a slight depression rmming to the spur. 

 Interior roughened; articular ridge rather strong but not overhang- 



1 The distribution here given is what I hivQ been able to verify from specimens in hand. Darwin 

 gives some foreign localities; it would be well to confirm them by dissection of specimens. Fritz Miiller's 

 Balanus improvisus, var. assimilis, and his supposed bastard between that and B. armatus, are clearly 

 B. amphUrite niveus. This extends the range southward to Santa Catharina Island, in southern Brazil. 



