173 



hypothesis of Wesenberg-Lund ('00) we should expect a predomi- 

 nance of the long-spined forms. 



Brachionus bakeri var. rhenanus Laut. Average number of 

 females, 118; of eggs, 138; but more abundant in previous years. 

 This is the third in numbers on the list of seven varieties, being 

 surpassed only by duniorbicularis and tuberculus. It includes about 

 one sixth of the individuals referred to this species. ' It is found 

 throughout the whole range of the seasonal distribution of the 

 species and exhibits the same peculiarities noted in-cluniorbicularis, 

 to which it is very closely related. The proportion of females to 

 eggs noted in this variety is very large; 5,284 to 5,485 in the grand 

 total. 



Brachionus bakeri var. brevispinus Ehrbg. Average number of 

 females, 795 ; of eggs, 390; but somewhat more abundant in previ- 

 ous years. It was found throughout the whole seasonal range of 

 the species, but not quite so abundantly in the latter as in the earlier 

 half of the summer, resembling in this particular the type. The 

 number of eggs carried in this species is in relation to the number of 

 females less than usual 3,906 to 795. 



Brachionus bakeri var. melhemi Barrois and v. Daday. Average 

 number of females, 49; of eggs, 49. More abundant in previous 

 years, especially in 1894, when it constituted over a fifth of the 

 individuals (25,764) in the largest pulse recorded for the species as a 

 whole 122,958 on July 30. In the aggregate in all years it includes 

 only about a ninth of the individuals referred to the species. This 

 form was originally described from Syria, but it is found in great 

 perfection in our plankton, even in the extreme type described by 

 Zacharias ('98b) as B. falcatus. It occurs throughout the whole 

 seasonal range of the species, its distribution being somewhat similar 

 to that of tuberculus. I do not find any constant tendency limiting 

 its occurrence to any part of the seasonal range. 



Brachionus bakeri var. tuberculus Turner. Average number of 

 females, 155 ; of eggs, 42 ; but very much more abundant in previous 

 years, especially in 1894, when it constituted almost half (55,332) of 

 the largest pulse of the species (122,958). This, the most divergent 

 of all the varieties, constitutes over a third of all the individuals 

 referred to the species. It occurs throughout the whole seasonal 

 range of the species, though the larger numbers were found in 

 1894-97 in the earlier part or middle of the summer. I find nothing 



