72 



BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



Hoek has described two new varieties: var. costatus and var. i^li- 

 catus,^ both taken from the bottom of the Sihoga and therefore from 

 some part of the Malay Ai'chipelago. Var. costatus was based upon 

 one specimen 14 mm. in diameter; var. flicatus 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. tintinnahulum can not be lightenad by the description of scanty, 

 immature, and imperfectly locahzed material. 



BALANUS ALGICOLA, new species. 

 Plate 12, figs. 3 to 3y. 



Tjii^e. — Cat. No. 15063, U.S.N.M., from Cape To^vn, growing on 

 algjB, collected by Wm. Ha,rvey Brown, United IStates eclipse expe- 

 dition, 1889. 



Distribution. — South Africa. 



Fig. 12.— Balanus algicola a, b, terga of two and d, c,f, scuta of three individuals, c, pakt of 



TIIE EDGE OF A RADIUS, SHOWING DENTICULATE SEPTA AND OPEN ENDS OF THE RADIAL PORES. 



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

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

 radii; smooth or somewhat ribbed. 



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



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



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

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

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

 The tergal border is rather narrowly deflected. Tlio basitergal 

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

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



1 Both of these names are preoccupied in Balanus. 



