REPORT ON THE CIRRIPEDIA. 11 



Devonian " is described. I learn from this note that Barrande has instituted a genus, 

 Plumulites, fur certain fossils regarded by him as the capitulum plates of sessile 

 Cirripeds ; this name Plumulites includes the genus Turrilepis proposed by Woodward 

 for a form which he regarded as bearing a scaly peduncle ; Barrande, " in regarding 

 his specimens as all capitulum plates, and not the scales of the peduncle, has based his 

 conclusions upon the external markings of the plates, rather than upon any such varia- 

 tion in shape and size as we should expect to find in the cajjitulum plates of a Lepadid.' 

 I have not been able to peruse the original work of Barrande; but judging from what 

 Mr. Clarke states about the close resemblance of Barrande's specimens and his, and in 

 the second place, from the figure Mr. Clarke gives of his specimens, the sessile nature of 

 this Silurian and Devonian Cirriped appears to me to be very problematical. A good 

 figure of the innermost side of the valve which is considered as the scutum of a sessile 

 Cirriped would perhaps show the impossibility of supporting the view of Barrande and 

 Clarke. The figure given resembles, by its triangular outline, the scutum of a Barnacle, 

 but several species of Scalpellum and Pollicipes have scuta of a triangular outline as 

 well. Finally, 1 need hardly recall the fact that they may be all capitulum plates, and 

 yet belong to a pedunculate Cirriped. 1 However, the question whether these plates 

 belong to a sessile or a pedunculate Cirriped must remain an open one; that they belong 

 to Cirripedia can hardly be doubted, and this granted, we learn from it that our know- 

 ledge as to the distribution of the Cirripedia in time is very imperfect, and in the second 

 place, that the conclusions arrived at, by comparing the living and the fossil forms, 

 must be received with the greatest reserve. 



"With respect to the relation between the geological history of the Cirripedia and 

 their occurrence at considerable depths, the information literature provides us with is 

 extremely insignificant. Even the approximate ranges of depth at which the larger 

 number of Cirripedia are found are not in our possession. Darwin (1854) saj's that 

 Balanus crenatus inhabits water down to 50 fathoms, and (1851) that most of the spc 

 of Scalpellum are inhabitants of deep water. With the exception of the Norwegian 

 Expedition of the " Voringen," the earliest attempts to increase our knowledge with 

 regard to the inhabitants of the great depths of the ocean were fruitless as regards the 

 Cirripedia. As far as I am aware the species of Scalpellum, dredged by Prof. 

 G. 0. Sars, and published in his lists of new Crustaceans and Pycnogonids of the 

 expedition of the "Voringen," are the only instances, recorded in zoological literature, of 

 animals of this order inhabiting the great depths of the ocean. In one of the letters, 

 addressed to Prof. v. Siebold, during the voyage of H.M.S. Challenger, v. Villemoes 

 Suhm stated that the only Cirriped often met with at a considerable depth, was the 

 genus Scalpellum ; but a careful examination of the collection put into my hands soon 



1 A third species of Plumulites (Plumulites newherryi) has been described by Mr. Whitfield from the Huron 

 (Genesee and Portage) shales (New York Academy of Science, March 1882). 



