228 BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



BALANUS ALLIUM Darwin. 



1854. Balanus aUiunt, DAKXVIN, Monograph, p. 2S1, pi. 7, figs. la-Id. 



Type. British Museum. 



Distribution. Raines Island, Great Barrier Reef. 



Besides the locality given above, Darwin had specimens on Porites 

 of unknown origin. The Museum has specimens, locality unknown, 

 growing on a coral with Pyrgoma. The size varies from basal diam- 

 eter 12.5 mm., altitude about 6 mm., to basal diameter 7 mm., altitude 

 5 mm. 



BALANUS ARCUATUS Hoek. 



1913. BftJaniis arena tits HOEK, S'/fto.</rt-Expe<litie, Cirripedia, Monographic 

 31 ft, p. 210, pi. 21, figs. 4-14 (lUinda, 9-13 meters). 



Distribution. Banda to the Sulu Archipelago (Hoek). Alba- 

 tross station D5156, near Tinakta Island, in the Tawi Tawi group of 

 the Sulu Archipelago, 18 fathoms. 



Three specimens grew on a calcareous plate of organic origin, 

 nature not determined. The largest is 10 mm. in greatest diameter. 

 They were dead when collected, but from one I obtained the opercular 

 valves, embedded in mud. They agree with Doctor Hoek's account, 

 particularly in the peculiarly arcuate shape of the terga; but the 

 spur is wider. The scutum has somewhat more closely placed growth- 

 ridges than his figure shows, and the articular ridge is longer, nearly 

 the whole length of the tergal margin. It is certainly related very 

 closely to B. alliwni, if indeed it can be held distinct. In the features 

 in which the Albatross specimens vary from Hoek's description, they 

 approach B. all turn. 



BALANUS CEPA Darwin. 



1854. Balaintfi cepa DARWIN, Monograph, p. 2S3, pi. 7, figs. 8a-Sc. 



Type. British Museum, from Japan. 



Distribution. Japan to the Philippine Islands on other barnacles, 

 shells, and I sis. 



Mogi, Japan, from the Imperial University of Tokyo ; on Balanus 

 trie/onus. Zamboanga, Mindanao, collected by Dr. E, A. Mearns; on 

 Balanus tintinnabulum zebra. Jolo, Jolo Island, on oysters and pearl 

 oysters, Albatross Expedition, 1908. 



Darwin says of this that the basis is " flat, obscurely permeated by 

 pores." In the specimens from Jolo, which could be removed entire, 

 the basis shows radial white and gray lines, as in B. anvphitrite ; but 

 these are caused by rather strong little ridges on the inside or upper 

 surface of the basis, which is not really permeated by pores, at least in 

 the examples I examined. It may be that some of the radial furrows 

 become closed over in some individuals. 



