230 THE AMERICAN NATURALIST. [VOL. XXXV. 
are comparatively rare, for the book as a whole is a remarkably 
trustworthy condensation of the chief facts of human physiology and 
hygiene. 
As to ** Social Ascidians.’’ — In a recent brief paper M. Maurice 
Caullery ! adds one more to the numerous instances brought to light 
in recent years tending to obliterate the distinction between social 
and compound ascidians. ‘The case now reported is likely to be 
noticed more than the others have been, in that it relates to the 
genus Clavelina, which is one of the ascidians most familiar to the 
general zoólogist, and is usually given in Merit um as a type of 
the social ascidians. 
In this genus the ascidiozooids, it will be recalled, bud from a 
stolon, but remain entirely distinct from one another, excepting for ; 
their connection with the common stolon. In the species here 
described (there are two of them) the ascidiozooids differ struc- 
turally in no way from a typical Clavelina ; but, instead of being 
connected to the common stolon only, they are fully imbedded in a 
common testicular mass also. 
It is obviously necessary, Caullery says, to establish a new genus 
for these species ; and the name proposed is Synclavella. 
Had the author’s acquaintance with the literature of this subject 
included the case of Perophora annectens described by me seven 
years ago, he would not, perhaps, have been so sure about the 
necessity of a new genus for his species. In this one species I 
showed (Proc. Calif. Acad. Sei, Series 2, Vol. IV, p. 37) that “in 
very many, though not all, of the colonies the ascidiozooids are as 
completely imbedded in a common test as they are in Botryllus or 
Goodsiria." 
This species is exceedingly abundant at various points on the 
California coast, and one may frequently observe transitional states 
between social and compound on the same rock, and apparently in 
the same colony. I may now add that, after having studied them 
for a number of years, I have about reached the conclusion that the 
social condition is the usual one; and that the compound con- 
dition occurs only occasionally, even in the same locality. At 
Pacific Grove, for example, where the most perfect instances of the 
compound phase have been found, I have, on several visits, failed 
to find any at all of this kind. It is an interesting fact, also, that 
lSur des Clavelines nouvelles (Synclavella 2.g.), constituant des cormus 
d'Ascidies composées, Comptes Rendus, No. 21, May 21, 1900, p. 1418 
