W. G. Van Name — Bermuda Ascidians. 389 



None of the specimens correspond exactly to specimens of S. 

 partita from Massachusetts (Wood's Hole); though some bear a 

 very strong external resemblance to them, even to the "alternate 

 striping of red and white in the apertures," mentioned by Verrill, 

 which is characteristic of S. partita; but as the differences are hardly 

 tangible enough to base a species on, it seems best to consider the 

 Bermuda form as a subspecies of S. partita. The specimen in Prof. 

 Verrill's collection, marked S. canopoides, does not differ specifically 

 from the others, though it certainly does correspond well with 

 Heller's (4) and Traustedt's (16) description and figures of that 

 species. 



This raises the question as to the status of S. partita (Stimpson) 

 as a species, and of its relations to <S. canopoides and other European 

 forms. Metcalf (11) has expressed the opinion that the New Eng- 

 land form is only a variety of Slyela aggregata of Northern Europe. 

 He has not, however, given any detailed statement of his reasons for 

 this belief. Unquestionably the two species are closely allied, but 

 if the New England form is only a variety of a European species, it 

 would seem more reasonable to regard it as a variety of S. cano- 

 poides, rather than of S. aggregata, especially as the latter is a 

 northern species, while S. partita is distinctly southern in its distri- 

 bution. This is, however, a point which I do not feel in a position 

 to decide without a considerable series of European specimens for 

 comparison, and in the present paper I shall confine myself to the 

 consideration of the relations between the Bermuda and New Eng- 

 land forms. 



Though Cynthia (Styela) partita was described half a century or 

 more ago, no account or figures of its internal anatomy have been 

 published as far as I am aware.* The following details are from 

 specimens taken at Wood's Hole, Mass., in July, 1901. They were 

 growing attached to the piles of a wharf, in large masses (sometimes 

 8 cm across), which contained as many as a dozen individuals closely 

 crowded together. The attachment was by the posterior end of the 

 body. Where individuals grow singly, they are often attached by 

 the whole ventral surface, or by a large part of it. In such speci- 

 mens the branchial siphon may be a little back from the anterior 

 end of the body. 



The body tapers rather rapidly at the anterior end, and the atrial 

 siphon is placed well forward and also directed more or less ante- 



* Except Professor Verrill's figures of the gonads in this volume (pi. ix, figs. 

 8, a, b, c), 15)01. 



