268 
EICHART) ASSHETON. 
blast o£ the g'ut and the larval envelope. I ara not quite sure 
whether I understand his theory, but it seems that it must 
imply a connection having been made with the larval envelope 
by way of the lips ' of the blastopore, and effected at an early 
stage of the growth in length, so that the allantois and its 
vessels represent a very much more anterior part of the gut 
than the urinary bladder of Amphibia, and that the hind gut 
arises as a dorsal diverticulum of the allantois. Or are we to 
believe that the hind gut of Amniotes is something new and 
that the anus of Amniotes is not homologous to the anus of 
Anamnia? 
Chapter V. 
The Gnal chapter on the placenta is full of interest and 
less controversial than the rest of this comprehensive and 
remarkable treatise. Probably, however, most zoologists 
w'ill be sorry that Hubrecht has not attempted to deal more 
thoroughly with the question of the value of tbe placenta as 
a guide to classification, though no one who has studied 
mammalian placentation wdll be surprised at his decision to 
postpone this most difficult subject. I feel, however, quite 
sure that Hubrecht must believe that the testimony is there 
to a large extent, and one will look forward to his exposition 
of it at some not distant date. 
I entirely agree with Hubrecht’s opinion that the diffuse 
placentation of the Lemurs is different from that of the true 
plicate forms of Ungulates, Cetacea, some Edentates, etc. 
In my paper of 1906“ I did,indeed, mention the Prosimiawith 
much hesitation (vide PI. 13) in connection with the plicate 
forms, but I felt then — and since having examined a speci- 
men kindly sent me from the Zoological Gardens by Mr. F. E. 
Beddard, F.R.S., I have felt more strongly — that the condition 
of Nycticebus may possibly have been derived from that of 
‘ I do not know, liowever, wliat in Hubrecht's opinion the relation 
betweeir the larval envelope and the blastopore lips may have been. 
^ ‘ Phil. Trans. Roy. Soc. Lond.,’ vol. clxviii. 
