INTRODUCTION. 
XXI 
tip, wliere it passes off. BaJanophylUa presents an excep- 
tion to this rule, -n’liich I liave found to hold good in all 
other examined cases. In this instance, the tentacles, which 
arc densely clothed with palpocils, seem to me destitute of 
external cilia, while all the scarlet parts are furnished with 
these latter. The ciliary currents flow doum the sides of 
the column, and up the conical mouth from the whole 
circumference of the disk. 
6. Reproductwe, System. The Actinaria increase by 
spontaneous fission, by gemmation, and by generation. 
Fission takes place either by a longitudinal division of the 
entire animal from above downwards, or by separation of 
small fragments from the edge of the base, which soon 
develop themselves into minute and apparently young indi- 
viduals. The former mode appears to be not uncommon 
with Antliea cereus (see infra, p. 169) ; and an imperfect 
form of the same produces double-disked individuals of 
Actinoloba and Actinia. The latter mode is common with 
several of the Sayartiadce (see pp. 19, 66, 86, 110). 
Gemmation, — the production of buds from the parent 
individual — occurs largely in the order before us, but prin- 
cipally in those which have a stony skeleton. According to 
Mr. Dana, whose classification I have followed, the Astr^- 
ACEA always bud from the disk, the Caryophylliacea 
invariably from the side or base. But a specimen of 
A.dianthus has come into my possession, — through the 
kindness of L. Winterbotham, Esq. of Cheltenham, — which 
has two young individuals projecting one from each side, 
at about mid-height, — an indubitable example of lateral 
gemmation. The animal has continued in the same condi- 
tion for nearly a year, with no tendency to separate its 
progeny. 
Generation is of course the normal mode of increase of 
the race. The sexes are sometimes united in one indi- 
vidual {S. troglodytes, p. 100) ; sometimes separate {Stom- 
pliia Churcliice, p. 225). The testes and the ovaries cannot 
be distinguished from each other by a cursory examination; 
each consists of a pulpy mass, usually of an orange or pale 
salmon-colour, attached to the free edges of the septa. The 
peritoneal membrane which invests each side of the septum 
is produced beyond the muscular layers in the form of 
a mesentery of two films in contact (Plate XI. fig. 1, e). 
At some distance from the edge of the septum, the films 
