NOTES AND MEMORANDA. 
105 
the ova and the spermatozoa both take their origin from cells 
of the Entoderm. Accordingly, the Hertvvigs propose to 
generalise their observation — a proceeding which appears to 
us to be as yet without justification. They still maintain — 
in spite of the observations of Ed. van Beneden and others — 
that all the Hydromedusae develop their genital products 
from Ectoderm. This really rests only on the observation of 
a certain number of medusa forms and of Hydra, and is op- 
posed to equally careful observations on Hydractinia, &c. 
Further, they expand their observations on Scyphomedusae 
(Acraspeda) and Anthozoa to the dimensions of a statement 
that all members of both these groups uniformly develop 
their genitalia from Endoderm. Very possibly both these 
large statements are true, but such is by no means demon- 
strated at present. However, the Hertwigs proceed further, 
and on this basis propose to remodel the groups of the nema- 
tophorous Ccelentera. They propose to abandon the division 
into Hydrozoa and Anthozoa, and to constitute two groups, 
one to contain the Hydromedusae which have ectodermal 
genitalia, the other to contain the Scyphomedusae and 
Anthozoa, which have endodermal genitalia, thus denying 
the supposed close relationship between the two kinds of 
Medusae, and making them mere homoplasts, one of the 
other. 
For the two new groups they propose the names Ectocarpa 
and Endocarpa respectively. Very possibly such a grouping 
may have to be ultimately adopted. There is no doubt that 
a sharp line cannot be drawn which shall separate Hydrozoa 
and Anthozoa, and the new division proposed would not be 
more wanting in definition than is the present. At the 
same time, should the grounds put forward by the Hertwigs 
prove really solid, the old terms proposed by Wilhelm Rapp, 
of Tubingen, for an exactly similar classification, will have 
to be adopted, namely, ‘^Exoarii and Endoarii,” 
It is strange that the Hertwigs should have overlooked 
their countryman’s contribution to this subject, published as 
long ago as 1829, and not so far from Jena Ueber die 
Folypen in Allgemeinen und die Actinien insbesondere,^ 
WeimaT). Yet further do the Hertwigs err in their reference 
to the history of the investigation of Coelenterate mor- 
phology, for, whilst discussing the appropriateness of the 
old tenns, Phanerocar])a and Cryptocarpa, for the designa- 
tion of the groups which they propose to establish, they refer 
those well-known terms to Edward Forbes (loc. cit., p. 624) 
insteail of to the illustrious Eschscholtz. 
Thp difficulty which presents itself most obviously in the 
