224 Prof: F. J. Bell on the - 
first it was merely for the evacuation of the genital products ; 
today itis true asexual reproduction; and, wide as is the 
physiological, just as wide if not wider is the historical gulf. 
Between the two there stand the phenomena of adaptation to 
environment; in some cases this has been so complete (deve- 
lopment of spines, marginal plates, odours) that the starfish 
fears no foe; in others, as in Ophiomastix, vegetative repeti- 
tion is capable of atoning for all or much that is lost; in 
others, lastly, neither strength of spine nor length of arm 
suffices ; and then the dangers to the species are atoned for by 
a modern recurrence to the ancient habit of fission. 
_ The account given by Prof. Hiickel of the different methods 
of reproduction may perhaps be conveniently modified, and 
put to stand thus :— 
A. Sexual reproduction. 
(a) With metamorphosis (‘‘metagenesis and internal gemmation”). 
(6) Without metamorphosis (viviparous Echinodermata). 
B, Asexual reproduction. 
(a) Fission, with repair. 
(6) External gemmation from a single arm. 
A tabular arrangement of the stages of reproduction and 
fission may be useful :— 
I, General break-up of the organism. Compare Palolo. 
TI, Gradual or regularized loss of the arm. Compare the Discophora. 
TII. Normal and combined evacuation of genital products through 
special pores. 
IV. Injury to arm by external enemy. Compare tail of lizard. 
V. Loss of arm (or division of disk) on irritation. 
VI. Arm (or disk) gives off buds. 
16, 17. Ophiactis Savignii. 
In addition to a sexradiate example of this very widely 
distributed species, there are three specimens, two of which 
are sexradiate, of a species, not now to be exactly determined, 
which would appear to belong to the genus Ophiacantha. Here 
the sexradiate condition may possibly be an accidental 
variety. ‘The specimens are all small and perhaps immature ; 
at any rate, they present no evidence of that viviparous con- 
dition which, as is well known, is seen in some, at any rate, 
of the sexradiate species of that genus. 
18. Astrophyton clavatum. 
Broken pieces indicate the presence at Ceylon of a species 
which has as yet been only recorded from Zanzibar, though 
the British Museum has also specimens from Mauritius. 
