72 



BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



Hoek lias described two new varieties: var. costatus and var. pli- 

 catus, 1 both taken from the bottom of the Siboga and therefore from 

 some part of the Malay Archipelago. Var. costatus was based upon 

 one specimen 14 mm. in diameter; var. plicatus upon two, the larger 

 of 10 mm. diameter. The open furrow of the tergum probably 

 means that both were young barnacles. Quite possibly both may 

 be the young of var. zebra Darwin. In any case, the very great 

 difficulty of reaching a satisfactory understanding of the forms of 

 B, tintinndbulum can not be lightened by the description of scanty, 

 immature, and imperfectly localized material. 



BALANUS ALGICOLA, new species. 

 Plate 12, figs. 3 to 3y. 



Type. Cat. No. 15063, U.S.N.M., from Cape Town, growing on 

 algse, collected by Win. Harvey Brown, United States eclipse expe- 

 dition, 1889. 



Distribution. South Africa. 



D 



FIG. 12. BALANUS ALGICOLA a, b, TEKGA OF TWO AND d, e,f, SCUTA or THREE INDIVIDUALS, c, PART OF 



TUB EDGE OF A RADIUS, SHOWING DENTICULATE SEPTA AND OPEN ENDS OF THE EADIAL PORES. 



Very small, conic or cylindric, usually growing in crowded clus- 

 ters; white, or sometimes with faint violet stains, chiefly on the 

 radii ; smooth or somewhat ribbed. 



Diameter 7 mm.; height 9 mm. (typical, cylindric form). 



Diameter 11 mm.; height 6 mm. (solitary, conic form). 



Scutum very broad, having widely spaced growth-ridges, alternate 

 ones forming teeth along the occludent margin; no radial striation. 

 A broad, shallow depression runs down the middle of the valve. 

 The tergal border is rather narrowly deflected. Tho basitergal 

 angle is cut off in varying degree, as shown in figure 12 d, e,f. The 

 articular ridge is moderately high, reflexed, with its lower end trun- 



1 Both of these names are preoccupied in Balanus. 



