REPORT ON BARNACLES OF PERU, COLLECTED BY DR. 

 R. E. COKER AND OTHERS. 



By Henry A. Pilsbry, 



Of the Academy of 'Satural Sciences, Philadelphia. 



Our knowledge of Peruvian Cirripedia is chiefly due to Charles 

 Darwin's "" Monograph on the Subclass Cirripedia," 1852, 1854, and 

 to a few records made by W. Weltner of specimens in the Museum 

 fiir Naturkunde in Berlin. The specimens collected by Dr. R. E. 

 Coker and Dr. W. H. Jones, U. S. Navy, have been studied in the 

 preparation of this report, which has been prepared at the request of 

 the Ministerio de Fomento of the Peruvian Government as a contribu- 

 tion to the knowledge of the aquatic resources of Peru. 



No parasitic cirripedes, or forms commensal on crabs, have been 

 found, although specially looked for on the Crustacea collected by 

 Dr. Coker. The apparent absence of such species on the west coast 

 of North and South America is remarkable. Further collecting will 

 doubtless add largely to the list of littoral barnacles, as well as to the 

 deep-water fauna, of which nothing is now known. 



The figures and descriptions are all from Peruvian examples. The 

 occasion has been taken to offer sufficiently enlarged figures to show 

 the details of the plates of Balanidcp. It is hoped they will make 

 the identification of specimens of this difficult genus much easier. 



KEY TO FAMILIES AND GENERA OF BARNACLES KNOWN TO OCCUR IN PERU. 



a\ Sessile barnacles. 



&\ Walls symmetrical, conic, or subcylindrical ; movable or opercular plates 



paired Family Balanid^e. 



c\ Wall composed of four compartments (the sutures sometimes obliterated 



externally) Genus Tetraclita. 



c^ Wall composed of six compartments. 



d\ Rostral compartment having overlapping radial areas at the sides, 



Genus Balanus. 

 d^ Rostral compartment having side wings or ahie overlapped by the 



adjacent lateral compartments Genus Chthamalus. 



b'. Walls asymmetrical; only two dissimilar movable plates, 



Family Verrucid.e. 

 Genus Verruca. 



Proceedings U. S. National Museum, Vol. 37— No. 1700. 



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