THE BABKACLES IN THE U. S. NATIONAL MUSEUM. 21 



lar, and generally the umbo of the carina is removed morc^ or less 

 from the apex. The named forms are as follows: 



S. stroeinil M. Sars. 



S. ohesuin Aurivillius. 



8. luridurii Aurivillius. 



S. aduncuni Aurivillius. 



S. grmnlandiciuii Aurivillius. 



S, cornuhiin Sars. 



S. angustuvi G. O. Sars. 



8. nyinphocola Hoek. 



8. iieptenti'lonale Aurivillius. 



Of these forms, iS'. angustuin and 8. nymphocola are distinct by the 

 quite apical umbo of the carina and the acute terga. 8. corivutuni 

 difl'ers from the others by the position of the umbo of the inf ramedian 

 latus, among- other features. In 8. gramlandicmn the umbo of the 

 carina, while not quite terminal, does not project, and the rostrum is 

 wider above than ])elow. 



All of the other forms {S. stroemii Sars, se2)tentr{onale^ ohesum., 

 luridum^ and aduncum Aurivillius) have the carina angular, the ros- 

 trum tapering upward, and the umbo of the inf ramedian latus at or 

 below the middle of the rostral margin. It seems to me \Qvy doubtful 

 whether the several forms of this type can bo distinguished as species. 

 Their slight differences are apparently due in part to age, but chiefly 

 represent, I think, local and colonial variations of 8. f<troemi!.,'^ a 

 species in which nearh" every colony l)rought up by the dredge has its 

 own slight peculiarities. 



The degree to which the basal whorl of plates is swollen varies with 

 age. Figures 1 to 5 on Plate I represent three individuals from one 

 cluster, drawn to the same scaled and selected from a continuous 

 series of variations in obesity, to illustrate this point, the old, ot)ese 

 examples having ovaries swollen with eggs. 



SCALPELLUM STROEMII M. Sars. 



Plate I, figs, fi, 7 (tyi)ical), and figs. 1-5 (variety). 



1859. S. stroemii M. Sars, Forhamllinger Vicieiiskabs-Selskabet i Cliristiania, Aar 



1858, p. 158, (Finmark, 40-50 fins. ). 

 1891. A', stroemii G. O. Sars, Forh. Videnskabs-Selsk. Aar 1890, p. 77. 



This species has been variously identified by Verrill, Hoek, and 

 Gruvel. On application to Prof. G. O. Sars I received two specimens, 



«Hoek's figure of *S'. stroemii (Cliallenger Report, Cirripedia, pi. in, fig. 6) is evi- 

 dently erroneous in the shading of the inframedian and upper latera, giving the 

 impression that these plates have subcentral umbones; also in the position of the 

 umbo of the scutum. The upper latus is figured as nearly three times as long as 

 wide, a proportion imlike any form of the group known to me. The specimen 

 requires reexamination. 



