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 inha])itod 

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

 s})ecies 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 Natioiuil Museum and 

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



iVntillean Province: B. t. antUlensis. 



Magellanic^ and Peruvian Provinces: B. t. concinnus. 



B. t. galapaganus. 



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

 B. t. peninsularis (C^ipe 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 Indo-Pacific, 

 Australasian, and West African races of B. tintmnabulwm 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 



BALANUS TINTINNABULUM TINTINNABULUM Linnaaus. 



Plate 10, figs. 1 to le. 



1758. Lepas tinlinnahuluni Linn.iius, Syst. Nat., ed. 10, p. 668. 



1838. Balanus dilatalus Schlutkr, Kurzgefasstea systematischos Vcrzeichrusa 



meincr Concliyliensaminlung, p. 38. 

 1854. Balanus iintinnahidwm, var. communis Darwin, Monograph, p. 195. 



The t3rpical 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 inadndssible in this 

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

 Montagu, another of Defrance. 



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

 ribbed longitudinally; colors varying from purplish j^ink to blackish 

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

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

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

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

 with livid pur])lc or in })art white, the slieath 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 scutmn (pi. 10, figs. Ic, Id) is buff, with dull, dark-purple 

 clouds; basiscutal angle rounded and ascending. Surface is strongly 



1 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. 



