MUSEUM OF COMPARATIVE ZOOLOGY. 85 
giving rise to the phenomena of young individuals interpolated between 
older ones. Representing, then, individuals by the budding zones from 
which they have arisen, we may convert the following formula of Semper 
into one based on our own nomenclature : 
E D H B G Cc F A 
un nen mae ee [en ~~ 
az, -3+0-0 4+0-1+0-0 4+1-1+0-0 4+0-2+0-0 4+1 
in which the succession of generations of zodids is 
Seg Raat Brgy 8, OF lt 
In the above formula A, B, ©, etc. represent zoöids; the numerals 
below the letters, the number of metameres of which each is composed ; 
0, an incomplete metamere about to be derived from a budding zone ; 
az, the anal zone. Written in accordance with my conception of the 
facts, this formula would read: 
(20) $ D(x) *C(*) #a(x) «Bir * b (x) xa(x) xa (x) *A, 
i 
which somewhat resembles Formula (15) of Halistemma, and signifies 
that two embryonic masses are left behind by the anal zone, of which 
the one anterior to the zoöids proper (represented by letters) goes merely 
to form the head parts, and is represented parenthesized. The second 
is caudad the zoöid, and may form a secondary “ anal zone” giving rise 
to new zoöids. From one zoöid two or more anal zones may take their 
origin. Thus, from the embryonic mass caudad of A there have arisen 
that caudad of b, which has given rise to b (x) * a (x), and that caudad 
of a, which has given rise to a! (x).1 
The most general formula given on page 81 undergoes many modi- 
fications in the different groups, but in the midst of these modifications 
certain laws are to be discerned, to some of which I have already called 
attention. I will now proceed to a discussion of the significance of 
these laws. 
The guincunx arrangement of individuals, which is so noticeable in 
1 From a study of surface views of many specimens of Autolytus collected 
at Newport during June, 1891,-I am convinced that the sexual individuals are 
produced by proliferation of cells in the metamere XTIT. or XIV. of “parent 
form,” —the last which remains behind after breaking off of sexual form. Rep- 
resenting the proliferating metamere by (%*), we may write the budding formula 
of Autolytus thus: 
(208) $% E(*) D(x) C(*) Be) Alk) 
in which the parenthesized asterisks indicate the proliferating, but not gemmif- 
erating anal metameres of the sexual form. (Cf. A. Agassiz, ’63, pp. 397-400.) 
