1898] NOTES AND COMMENTS 375 
record of all deaths which came to his knowledge, and he finds it 
average 8 to 10 a year. As he points out, Washington has estab- 
lished a colony of beavers in the National Park, and it is a complete 
success. The animals are kept to a woody valley through which 
runs a small water-course, and they there construct their dams and 
tunnels, quite familiarised to the occasioned presence of man, who 
can watch their daily life and works unheeded. He hopes that 
France will similarly protect the few last beavers remaining in the 
Camargue delta, and we cordially echo his sentiments. 
A. T. MASTERMAN ‘ON THE DIPLOCHORDA’ 
SOME preliminary notes by Mr Masterman in the Proceedings of 
the Royal Society of Edinburgh, for 1896, and also in the Zoologischer 
Anzeiger, paved the way for a more detailed paper of great interest 
in the Quarterly Journal for Microscopical Science (vol. xl., 1898). 
The paper is divided into two parts—(1) on the structure of 
Actinotrocha, and (2) on that of Cephalodiscus. As the result of an 
exhaustive study of Actinotrocha (the curious larval form of Phoronis) 
by means of sections, Mr Masterman comes to the conclusion that 
the close similarity in structure to the three members of the group 
now commonly called Hemichorda points to a genetic connection, but 
that Phoronis and Cephalodiscus should be considered as constituting 
a distinct sub-division of the Chordata, for which the name of Diplo- 
chorda is proposed, owing to the possession by its members of paired 
lateral notochords. Balanoglossus is supposed to represent a later 
phylogenetic stage, in which these lateral notochords have fused in the 
median line. As there are certain animals which have always been 
objects of disagreement on account of their generalized types and the 
doubtful nature of their genetic relationships, so, too, there have 
always been certain organs or structures around which controversy 
has continually raged; the notochord is one of these, as students 
of the literature of Balanoglossus are well aware. If Mr Masterman’s 
views are correct, and the paired structures he describes both in 
Actinotrocha and in Cephalodiscus are really of notochordal value, he 
has established a fact of the greatest scientific interest and phylo- 
genetic importance, and we cannot but think he has made out a very 
good case for the homology. The figures on plates 25 and 26 are, we 
think, especially instructive, but they are nevertheless not universally 
regarded as convincing. Mr 8S. F. Harmer, whose views on the noto- 
chord of Cephalodiscus have been expressed in the Zoologischer Anzeiger 
(vol. xx., p. 342), while fully agreeing with Mr Masterman as to the 
relation of Phoronis with Balanoglossus, does not admit the homologies 
with Cephalodiscus, on which the main argument depends. Mr 
Masterman claims to show that the structure described by Mr Harmer 
as the notochord in Cephalodiscus is really the subneural gland, and 
