MUSEUM OF COMPARATIVE ZOOLOGY, 83 
origin in the embryo, the formula would have to be written somewhat 
differently ; namely, thus (16) :— 
3% Cat ce be ax Bat dx cx br ax Aex de ck bk ak ax yk Be ax [A] 
In a species of Pennaria, common on our coast, which is probably 
Pennaria tiarella, McCready,’ I have noticed the presence of a similar 
law of budding. The whole stock lies in one plane, the lateral branches 
arising alternately from the right and left of a central stock, like the barbs 
of a feather. These lateral branches give rise to a series of secondary 
ones, which are all placed on the same (axial) side of the branch. Each 
branch, of whatever degree, originates as a bud bearing a polyp. From 
the elongating stalk of this terminal polyp, buds arise, — the beginnings 
of branches of the next higher order. The stock may be represented by 
the following formula ; — 
A 
* 
| 
de — 
| 
cr — 
ge d 
* 
be —— 
a 
B * 
c * | | 
* * a eT 
| 
(17) #»D--- - - - - - - -- 
| 
ax — — 
| 
be — 
| 
c* 
* 
B 
Expressed in a linear series, this formula may be written :— 
(18) w Dx Ce Bece be ax Ax dec beat ax Be ax 
which is identical in form with the second formula (16) given for Hali- 
stemma. 
1 This species is figured by Leidy (’55, Plate 10, Figs. 1-5) and Verrill (’78, Plate 
XXXVII. Fig. 277). An allied species, P. gibbosa, is figured by Louis Agassiz 
in the “ Contributions” (Vol. III., Plate XV. Fig. 1). In describing P. Carolinii, 
Weismann (Entstehung der Sexualzellen, p. 122) says that the lateral hydranths 
do not possess the capacity of giving rise to new lateral hydranth-buds (of a higher 
order). But, as indicated above, P. tiarella seems to do this regularly. Leidy’s 
and Verrill’s figures show the same thing. 
