igii] 



ASCIDIANS FROM THE COASTS OF CANADA. 



115 



(i) in quantity. 

 Amaroucium sp. A, 

 Synoicum (?) sp. A, 

 Trididemnum sp. B, 

 Sycozoa [Colella] sp., 

 Holozoa [Distaplia] sp. A, 

 Polycitor (Eudistoma) sp. A, 

 Clavelina sp., 

 Perophora annectens, 

 Katatropa yakutatensis, 



(2) occasional. 

 Corella rugosa, 

 Chelyosoma productum, 

 Caesira pacifica, 

 Katatropa Vancouver en sis, 

 Cnemidocarpa joannae, 

 BoUenia villosa, 

 Pyura haustor, 



Styela montereyensis. 



Dredgings made in a few fathoms (5 to 10) yielded the following :- 



(i) in numbers. 

 Amaroucium sp. A, 

 Synoicum (?) sp. A, 

 Trididemnum sp. B, 

 Clavelina sp., 

 Ascidiopsis columbiana, 

 A. paratropa, 

 Corella rugosa, 

 Chelyosoma productum, 

 Caesira apoploa, 

 Cnemidocarpa joannae. 



(2) occasional. 

 Amaroucium sp. B, 

 Synoicum (?) sp. B, 

 Leptoclinum [Diplosoma] (?)sp., 

 Holozoa [Distaplia] sp. B, 

 Polycitor (Eudistoma) sp. B, 

 Katatropa uclueletensis, 

 Styela gibbsii, 

 Pyura haustor, 

 Tethyum aurantium, 

 T. igaboja. 



BoUenia villosa. 



Dall has remarked that the fauna of the inner channels of the 

 British Columbian archipelago is of a distinctly more northern character 

 than that of the open coast. This is well shown in the Ascidians. The 

 list from Departure Bay includes arctic forms that are not represented 

 at Ucluelet and among the Ucluelet species are a number of southern 

 forms that do not occur at Departure Bay. It may be noticed that the 

 arctic species of Departure Bay are not as plentiful and are not found in 

 as shallow water as the corresponding species of the Atlantic Coast at 

 St. Andrews. 



(C) . Some general features of interest. 



Material for studying the early development of many of the Asci- 

 dians can be obtained very easily, as in many cases the eggs are retained 

 in the parent and only the free-swimming larvae escape. This is the 

 condition of affairs in practically all of the compound Ascidians, (those 

 found at the stations). In the majority of the simple forms the eggs are 

 not retained, apparently because the oviduct opens into the atrium very 

 near the base of the atrial siphon and the strong current present at that 

 point carries the eggs out. In some genera and species the oviduct opens 



