XIV 



Key to the Hydroids of Eastern Canada. 



BY 



C. McLean" Fraser. 

 ("With 109 Figures.) 



INTRODUCTION. 



A recent paper contained a complete list of the hydroids that have been found 

 in the waters of Eastern Canada, so far as is known, with synonymy and distribution 

 of each species as related to this area and the literature i}ertaining to it.^ In the 

 present paper the same species are considered and an attempt is made by key, short 

 description and characteristic figure, to put in concise form for handy reference, a 

 means of diagnosing at least the typical hydroids. The investigator who wishes to 

 study more minute details, will find them given in the papers referred to in the 

 bibliography in connection with the previous paper. 



No new matter is introduced. In some cases where the writer had not previously 

 described the species, the description was made directly from the specimen, but in 

 substance this would naturally be similar to descriptions given by others. Similarly 

 many of the drawings have been made specially for this paper. Descriptions given 

 in, and drawings made for, previous papers, have been used in many instances, but 

 only in cases where specimens of the species recorded by other investigators were not 

 available for description have quotations or copies been madle from other authors. 

 In the list there were thirteen of these species and in some other cases the descrip- 

 tion of the gonosome had to be obtained, but in all cases the authority for the 

 description or figure has been given. The specimen of Lafoea symmetrica obtained 

 some years ago at Canso has been lost and the drawing is made from a sketch made 

 at the time, but it seems to agree with that given by Bonnevie, although it may not 

 be exactly typical. Two species described by Stimpson, viz., Eudendrium cingulatum 

 and Grammaria gracilis, were not figured by him, and apparently they have not been 

 described or figured since, hence no figures of these appear. The only difference 

 between Tuhularia spectabilis and Tuhularia tenella seems to be one of size, if that 

 is sufficient difference to separate species. As T. spectahilis is too large to admit of 

 the enlargement that is used throughout, the difference in size could not readily be 

 sho"wn, hence there is no figure given of T. teneUo. All drawings taken from other 

 sources have been reduced to one-third diameter. Figures 20, 21, 23 and 25 have been 

 magnified but little, figures 37, 52, 53, 54, 56, 61, 69, 76 are magnified 30 diameters, 

 figures 4, 6, 9, 10, 11, 26, 41 are magnified 15 diameters and the remainder of the 

 figures 10 diameters. 



For a copy of a plate containing the figure of Dicoryne flexuosa, I am indebted to 

 Mr. Dayton Stoner, of the State University of Iowa, and for a copy of the figure of 

 Tetrapoma quadridentahim, as well as the description, and for the description of the 

 coppinia of Lafce a pygmcea I am indebted to Dr. A. G. Huntsman, of the University 

 of Toronto. Mrs. Fraser has made the drawings for the paper. 



Although the same species are here treated, there is practically no duplication 

 of what is included in the previous paper. It seems entirely unnecessary to repeat 

 the synonymy and distribution in what is intended t-o be merely a handbook for 



1 Hydroids of Eastern Canada. Contributions to Can. Biol., 1917, pp. 329-370, Supp. to 7th 

 Ann. Rept., Department of Naval Service. 



137 



