THE SESSILE BARNACLES. 55 



From the consistent distribution of American forms, of which large 

 series of carefully localized specimens are available, it may fairly 

 be inferred that most tropical and subtropical coasts are inhabited 

 by one or more subspecies of B. tintinnabulum, and that these sub- 

 species are just as definitely local in distribution as most other inver- 

 tebrates of the littoral faunas. So far as American forms are con- 

 cerned, the collections of the United States National Museum and 

 Academy of Natural Sciences show the distribution to be as follows : * 



Antillcan Province: B. t. antillensis. 



Magellanic and Peruvian Provinces : B. t. concinnus. 



B. t. galapaganus. 



Panarnic Province: B. t. coccopoma (Panama to Mazatlan). 



B. t. peninsularis (Cape St. Lucas). 



Calif ornian Province: B. t. calif ornicus. 



The collections before me afford a little information upon the dis- 

 tribution of Old World forms. Some new data are recorded for 

 Japanese and Philippine races; but the distribution of Lido-Pacific, 

 Australasian, and West African races of B. tintinnabulum remains in 

 a chaotic condition. For the convenience of American naturalists, 

 descriptions and figures are given of the forms commonly brought by 

 ships to our ports, as well as of a few new subspecies 



B ALAN US TINTINNABULUM TINTINNABULUM Linnaeus. 



Plate 10, figs. 1 to le. 



1758. Lepas tintinnabulum LINN.EUS, Syst. Nat., ed. 10, p. 668. 



1838. Balanus dilatatus SCHLUTER, Kurzgefasstea systematischea Verzeiclinisa 



meiner Conchy liensammlung, p. 38. 

 1854. Balanus tintinnabulum, var. communis DARWIN, Monograph, p. 195. 



The typical form of this species was called var. communis by Darwin. 

 His plan was to give this name to the typical or usual form of all 

 species having several varieties. The name is inadmissible in this 

 connection, as there was a prior Balanus communis of Pulteney and 

 Montagu, another of Defrance. 



The barnacle is "conic or tubulo-conic, smooth or moderately 

 ribbed longitudinally; colors varying from 'purplish pink to blackish 

 purple, often in obscure longitudinal stripes; orifice of the shell 

 rounded-trigonal" (Darwin). Size large, the diameter ordinarily 

 50 to 65 mm. in conic forms. The radii are wide, usually in part 

 transversely grooved. The walls are not very thick, stained inside 

 with livid purple or in part white, the sheath dirty white, with 

 fleshy or purplish gray in the parietes. The interior is slightly ribbed 

 near the base. The basis is white and smooth inside. 



The scutum (pi. 10, figs, Ic, Id) is buff, with dull, dark-purple 

 clouds; basiscutal angle rounded and ascending. Surface is strongly 



i Data are lacking on the forms of the whole east coast of South America; also the continental coasts 

 of the Gulf of Mexico and Caribbean Sea. 



