322 ASAJIRO OKA AND ARTHUR WILLEY. 
N.B.—Since the above was written I have seen for the first 
time the exhaustive work of Fernand Lahille, entitled ‘ Re- 
cherches sur les Tuniciers des cétes de France,’ Toulouse, 
1890. Lahille devotes considerable attention to what have 
been spoken of above as tentacle-like processes of the larva, 
figures them in many larvee, and gives an excellent figure of 
the metamorphosing larva of Styela glomerata. He gives 
an opinion as to their significance which I cannot entirely 
endorse in the light of my own researches on the “ Post- 
embryonic development of Styela,”? commenced last August 
at Plymouth. However, I hope to return to this question on 
a future occasion. Lahille raises an objection to von Drasche’s 
genus Didemnoides on the ground that the thickness of 
the cormus is not an anatomical character, and that the dis- 
tinction between thick and thin colonies is a purely subjective 
one. There is no doubt some truthin this; but the difference 
between a compound Ascidian which possesses, say, a very few 
spicules, and one which possesses none at all, would appear to 
be no more fundamental than that between a colony whose 
mode of growth resulted in the production of a fleshy mass 
and one which grew in the form of a thin leathery crust. 
As stated above, von Drasche intends by Didemnoides a 
fleshy form of Leptoclinum, the test containing spicules, and 
the Ascidiozooids having four rows of stigmata in the bran- 
chial sac. Lahille,on the contrary, applies the name Didem- 
noides to those Didemnidz which are characterised by the 
absence of spicules, and the possession of three rows of 
stigmata in the branchial sac. 
The compound Ascidian which we have described above has 
spicules in the test, and four rows of stigmata in the bran- 
chial sac. But as it would be too absurd to call the new 
form “Sarcoleptoclinum,” we shall persist in regarding 
the genus Didemnoides from the point of view of von 
Drasche.—A. W. 
