On the Variation of Haliclystus octoradiatus. 
By 
Edward T. Browne, B.A., 
University College, London. 
With Plate 1. 
A NorMAL specimen of Haliclystus octoradiatus, Clark, 
has eight adradial groups of tentacles; eight adradial genital 
bands ; eight colleto-cystophors, one midway between every 
two groups of tentacles ; and four internal, interradial septa. 
The variation in number, shape, and symmetry of these 
organs forms the subject of this paper. The specimens were 
collected by the officials of the Marine Biological Association 
at Plymouth during November, 1892, and the spring of 1893. 
Texamined 154 specimens, and found 120 specimens perfectly 
normal and 34 specimens abnormal. Some of the abnormal 
forms are beyond doubt good cases of congenital variation, 
and others are cases of an imperfect regeneration of organs 
damaged or completely destroyed by injury. Congenital varia- 
tion is usually shown by an increase or decrease in the number 
of organs, which may either vary together or separately. 
Only three specimens show a numerical variation in all the 
organs. One has six groups of tentacles, six colleto-cystophors, 
six genital bands, and three internal septa. Two specimens 
have twelve groups of tentacles, twelve colleto-cystophors, 
twelve genital bands, and six internal septa. In the last two 
specimens the increase in the number of organs is not followed 
by a corresponding increase in the amount of tissue. Each 
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