276 Some Remarks on PlumuUtes Jamesi. 



series. The arrangement of the plates is as follows : The outer series 

 (or lower series, as it appears in the figure), has the concave side of 

 the series formed by the rapidly deflected lateral margin of the plates, 

 with the apex of each valve on the concave side. The inner series (or 

 upper series, as it appears in the figure), has the convex side of the 

 series formed by the rapidly deflected lateral margin of the plates, 

 with the apex of each valve on the convex side. These facts indicate 

 that the two series of plates are in their normal position, unless, it be 

 a fact, that the curve is the result of accident, and that the first plate 

 in the lower series is a little moved out of place. 



In the cabinet of C. B. Dyer, Esq., there is a specimen showing an 

 interior view of a series of six plates. The exposed surface of three 

 plates has a length of yV\ inch, where the plates are yf^ inch wide. 

 The specimen has the appearance, to the unaided eye, of a small an- 

 gular gutter of smooth overlapping plates, having one side three times 

 as wide as the other, but an ordinary glass will detect the tracing of 

 the transverse lines, that mark the other side of the plates. The 

 narrow reflected margin, on one side, forming, with the broader ex- 

 panse of the plates, a gutter, is exactly such a view, as we would 

 expect to find, by looking at the interior of the second, third and 

 fourth plates of each series in figure 19 ; other plates, however, in 

 this figure, would lead one to expect to see a more gradual curvature, 

 in the form of the gutter. 



The two series of plates must, therefore, be regarded as distinct, 

 though they might have been connected at the bottom of the depres- 

 sion formed by bringing together the abrupt sides of each. They 

 never could have been arranged, in the overlapping style of the plates 

 in Loricula puldwlla, and other Cirripedes. Nor does there appear to 

 be any reason for supposing, that any other plates were joined or in- 

 terlocked with either of these two series, forming with these a pine 

 cone arrangement. 



The sessile Cirripedes, according to Mr. Charles Darwin, are first 

 found, in the Eocene Tertiary, and subsequently abound, in the more 

 recent deposits, and in the present seas. Our specimen is not a sessile 

 Cirripede, because it did not attach itself to another object. The 

 oldest pedunculated Cirripede, known to Mr. Darwin, was from the 

 lower Oolite, but since his great work, the naturalists have found 

 them, at a much earlier period and now commonly refer numerous 

 Silurian Crustacea to this class. Mr. Darwin, says: (monograph of 

 the fossil Lepadidce or pedunculated Cirripedes of Great Britain). 



" That in the several orders of Cirripedia such important difierences 

 of structure are presented, that there is scarcely more than one great 



