EEPOET ON THE TUNICATA. 
259 
Didemnoicles, Trliich would therefore lapse as Della Valle’s name has the priority, (3) it 
may hare some peculiarities of its own distinguishing it from both Leptoclinum and 
Didemnoicles, and necessitating the employment of aU three sections. Delia Valle’s 
figures and remarks^ do not decide the matter, and therefore Tetmdidemnum gigas, 
Della Valle, must be provisionally placed on one side until more is known in regard to 
its structure and affinities, 
I am not, however, inclined to ascribe very much importance to the number of rows of 
stigmata, since species difiier in that respect which uppear to be otherwise closely allied, 
and I have found in one new species of Leptoclinum (see below) three rows and four 
rows of stigmata present in different Ascidiozooids of the same colony. Consequently, 
I only use the number of rows as a diagnostic feature in conjunction with other char- 
acters, and I regard Didemnoicles as being quite as closely related to the thick fleshy 
species of Diclemnum, although it has four rows of stigmata, as it is to the thin incrust- 
ing species of Leptoclinum. I therefore divide the family into genera according to the 
following Table : — 
Didemnid^. 
Colony thick and ikshy. Colony thin, incrusting. 
Three rows of stigmata. Four rows of stigmata. Four rows of stigmata. Six rows of stigmata. 
I I . I I 
Didemnum. Didemnoides. Leptoclinum. Eucodium. 
Further remarks as to the affinities of the groups will be found under the generic 
descriptions. 
The species of the Didemnidse have been described chiefly by Savigny, Milne- 
Edwards, Giard, Delia Valle, and von Drasche. The majority of them belong to the 
genus Leptoclinum, which has a wide distribution, mainly in shallow water. 
In the Challenger collection only the two commoner genera Didemnum and 
Leptoclinum are with certainty represented, and the maj-ority of the species belong to 
Leptoclinum. The genus Didemnoides contains two species found by von Drasche in 
the Adriatic and on the coast of Normandy. Possibly Leptoclinum cavpenteri, Lepto- 
clinum japonicum, Leptoclinum jacJiSoni, ecoA Leptoclinum ruhicundum, might be referred 
to this genus instead of to Leptoclinum. 
In regard to Euccelium, the only undoubted member of the genus that I know of 
is Savigny’s Eucoelium hospitiolum, which differs markedly from all other species of the 
family in having six rows of stigmata in the branchial sac. Giard’s Eucoelium 
parasiticum is probably, as von Drasche supposes, merely a species of Leptoclinum. It 
has only four rows of stigmata in the branchial sac. 
1 Nuove Contribuzioni, &c., p> 50. 
