MUSEUM OF COMPARATIVE ZOÖLOGY. 75 
rise to new polypides. As a matter of fact, the secondary rows often 
make. a greater or less angle with the primary ones, and as a result 
lateral branches are formed. Taking this character into account, the 
Cristatella formula might be written : — 
* 
* b 
*a, — a | 
| [*] 
x8 — xa — A 
| 
(6) #b — WB — [8 
| 
ka mug 
* 
This representation indicates the fact that the first formed buds (A, a, «, 
etc.) are lateral ones; the second, median (Davenport, ’90, p. 106). 
Intermediate stages between the condition in Plumatella, in which an 
indefinite number of polypides and gemmiparous masses can be budded 
off from pre-existing gemmiparous masses, and the condition in Crista- 
tella, in which only two such arise, occur apparently in some species of 
Plumatella, in which, as Braem (’90, p: 31) has shown, few polypides 
are produced from any gemmiparous mass, and all but two of these gen- 
erally do not develop. In the young corms of Cristatella, on the other 
hand, more than two polypides may thus arise. 
Other Ctenostomata show a regularity in the budding process similar 
to that of Paludicella, and exhibit instructive variations upon it. 
Victorella, an interesting Ctenostome occurring in slightly brackish 
water, and first described by Kent (70) in 1870, possesses, according to 
the pregnant observations of Kraepelin (87, pp. 75, 76, 154-157), a 
stolon-like tube, from which at intervals polypide-bearing “ cylindrical 
cells” arise. Kraepelin (°87, pp. 155-159) has shown it to be in the 
highest degree probable that the protrusion of the body wall in the neck 
region of the polypide of Paludicella is the homologue of the “cylindrical 
cells ” of Victorella, and that the remainder of the zoocia of Paludicella 
is homologous with the “stolon” of Vietorella. While in Victorella the 
cylindrical cell is developed to such an extent that the retracted poly- 
pide is still included within it, and the stolon remains of small calibre, 
in Paludicella, owing to its shortening, the retracted polypide must seek 
refuge in the stolon, whose diameter is consequently increased to receive 
it. Evidence for this is found in the stolon-like nature of the youngest 
zoœcia of a hatching winter bud of Paludicella Ehrenbergii, and in the 
elongated cylindrical cell of the adult Palndicella Mülleri, Kraepelin, 
