176 Professor MacGillivray on the Cirripedia. 



always extremely small and oblong, or elliptical, but I have seen many 

 specimens large and small, in which it was altogether wanting. I have 

 also seen the two upper pieces wanting, in which case the aperture was 

 not notciied above, as it usuallj' is. 



The colouring is also subject to variation. Generally the tegmen is 

 deep purplish-brown, with the ears still darker; the peduncle dark- 

 brown above, pale or hyaline-grey below. Often, however, the tegmen 

 is dotted or streaked with brown internally, the ears still more so, and 

 sometimes they are whitish on the inner side and spotted with brown. 



I apprehend, therefore, that authors have made more species than 

 nature has presented to them ; and that Otion Cuvierii, and Otion Blain- 

 villii, are one and the same. Otioti Rissoanns agrees precisely with many 

 specimens of the present species. Otion sacuti/era of Coates, from the 

 Cape of Good Hope, finds plenty of representatives among my speci- 

 mens. On all the vessels it was the same species, exhibiting the same 

 variations. The references, then, are : — 



Lepas aurita. Linn. Sys. Nat. 110. 



Lepas leporina. Poli. Test, plate 6, fig. 21. 



Lepas aurita. Brug. Diet. 66. 



Lepas aurita. Cuv. Mem. du Mus. ii. plate 5, fig. 12. 



Otion Cuvierii. Leach. Encyclop. Brit. Suppl. iii. 170, plate 57. 



Otiou Cuvierii. Lamk. Anim. s. Vert. v. 685. 



Otion Cuvierii. Gould. Invert. Massach.23. 



Gymnolepas Cuvierii. Blainv. Malac. plate 84, fig. 1. 



Lepas cornuta. Mont. Trans. Linn. Soc. xi. 179, plate 12, fig. 1. 



Otion Blaiuvillii. Leach. Encyclop. Brit. Suppl. iii. 178, plate 57. 



Otion Blainvillii. Lamk., Anim. s. Vert. v. 410. 



Otion sacutifera. Coates' Journ. Acad. Nat. Sc. Phil. vi. 132. 



Otion sacutifera. Lamk. Anim. s. Vert. Vesh. v. 686. 



Dimensions of several individuals. 



The principal circumstances observed with respect to these five 

 species of Barnacles, generally, are the following ; — 



They occur on the vessels promiscuously, without any order or 

 predilection as to association. 



Five of the vessels were coppered, and one Iron. 



All the species occurred on the iron vessel, excepting Lepas 

 Nauta, which was met in comparatively small numbers only on one 

 of the vessels. 



The Otion and the Cineras occuri-ed on the copper sheathing, but 

 sparsely, and principally on or near the nails, which were more free 

 of oxidation ; but they were most abundant on the wood and pitch, 

 just above the sheathing, and about the stern, more than on the 

 sides and bows, and especially on and near the seams. 



The Lepades were larger and more numei'ous on the stern and 

 rudder, both on the wood and on the pitch. 



Lepas anatifera and L. incurvata often occurred contiguous, with 



