353 
In the region of Nanaimo, of course, the boreal element is pre- 
dominant, represented by Scalpellum gruvelianum, Balanus glandula, 
Balanus hesperius, and Balanus crenatus. As to the latter I accept 
Pilsbry’s hesitation (1916) in acknowledging the statements from 
the Tropics and more Southern localities, given by previous authors. 1 ) 
Balanus glandula is more eurytherm, going down to Southern Ca- 
lifornia. 
In the Californian region we again encounter other character- 
istic species, viz. Scalpellum californicum, Nlilella polymerus, Chta- 
% 
malus fissus, Balanus tintinnabulum forma californica, and Tetraclita 
squamosa forma rubescens; these seem to be restricted to this re¬ 
gion, neither were they met with in the Bay of Panama, where 
Balanus tintinnabulum is instead represented by the beautiful forma 
coccopoma. 
In the Panamic region the interesting large Catophragmus Pils- 
bryi was met with for the first time; this species has a close re¬ 
lative in the Antillean region, and seems to contribute to the evid- 
ences of the past connection across Central America. — 
In papers dealing with the cirripeds it has frequently been 
stated that this group is of small biogeographical interest, as most 
of the species only occur in small numbers, and the others mostly 
have a worldwide distribution. Evidently most students of this group 
have overlooked the faet, recently so illustriously evinced by Pils- 
b ry (1916), that the widely distributed species tend to an obvious split¬ 
ting up in local races, when they do not direetly live an epibiotic 
planktonic life like most Lepas- and Conchoderma- species; and even 
here sometimes local races may be demonstrated. On the other 
hånd, such forms as several Elminius-spQciQS , Chamæsipho columna, 
Mitella polymerus, and Mitella sertus play a predominent part in 
the faunistic features, owing to their abundant occurrence in their 
special regions, and are thus well apt to serve as biogeographic 
character-animals. 
As to the more scantily occurring species, it is true that they 
play no predominant part in the biogeographical communities; never- 
*) Darwin (1853) mentions Balanus crenatus from the Mediterranean, 
Algoa Bay (South Africa), and Jamaica, Gruvel (1905) from Ile King 
(in the Bass Strait), Peru, and Wasin in British East Africa. 
Vidensk. Medd. fra Dansk naturh. Foren. Bd. 73. 23 
