110 BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



BALANUS POECILUS Darwin. 

 1854. Balanus poecilus Darwin, Monograph, p. 246, pi. 5, figs. 3a, 36. 



Type. — British Museum, 



Distribution. — West coast of South America, attached to an Avicula 

 (Cuming) . 



Shell fragile, tubulo-conical; fine dark-rose color, freckled with 

 transverse, sharply pointed, fine, zigzag white lines, and obscurely 

 striped longitudinally. Basal diameter one-half inch. 



Scuta dull red with a white band along the tergal margin, externally 

 smooth; articular ridge moderately developed, slightly reflexed. There 

 is no adductor ridge. There is a distinct pit for the lateral depressor 

 muscle, 



Tergum with the scutal margin unusually prominent, toothed; 

 longitudinal furrow shallow, the edges not folded in. Spur short, 

 barely one-third the width of valve, with the lower end sharply 

 truncated, parallel to the basal margin. 



Walls very fragile; radii fragile, broad, their summits moderately 

 oblique. Basis with an underlying cancellated layer. 



Cirri, first pair with one ramus longer by about four segments, the 

 shorter ramus with protuberant segments. Sixth pair with segments 

 much elongated, but bearing only four pairs of spines. 



This species is not contained in the United States National Museum, 

 and seems to be known by only one group of specimens, with the 

 indefinite locality recorded above. The above details are abbre- 

 viated from Danvin's description. It does not differ much in essen- 

 tial characters from B. amphitrite, but the absence of an adductor 

 ridge of the scutum and the sharply truncated spur of the tergum 

 are sufficient to distinguish it. 



BALANUS ALATUS Hoek. 



1913, Balanus alaius Hoek, /Siftogra-Expeditie, Monographie 30&, p. 175, pi. 15, 

 figs. 1-8. 



Type. — Sihoga station 97, latitude 5° 49' .7" north, longitude 

 119° 49' .6" east, northeast of the Sulu Archipelago, 564 meters. 



B. alatus was founded on two specimens, having a diameter of 

 about 3.25 mm. A few specimens which I refer to this species were 

 taken at Albatross station 5163, in the Tawi Tawi group of the Sulu 

 Archipelago, off Observation Island, in 28 fathoms. The basal 

 margin of the scutum is shorter than the tergal margin; maximum 

 diameter of the base about 9 mm. 



BALANUS POECILOTHECA Kriiger, 



1911. Balanus poecilotheca Keuger, Beitrage zur Cirripedienfauna Ostasiens, 

 Abh. der Math.-Phye. Klasse der K. Bayer. Akad. der Wissenachaften, 

 vol. 2, Suppl.-Bd., 6 Abh., p. 48, pi. 1, figs'. 2c-e; pi. 3, fig. 32. 



