416 
W. A. HASWKLL. 
history there are a number of important points that have not 
yet been determined — notably the processes of maturation 
and fertilisation, and the early segmentation phases. Since^ 
however, the portions of the development which I have 
succeeded in tracing reveal certain phases that are quite 
unique in character, it appears to me expedient to publish 
these observations as a first contribution to our knowledge 
of the subject. 
In addition to Temnocephala fasciata, T. minor, T. 
dendyi, and T. qnadricorn is, as well as Craspedella 
spenceri, have been made the subjects of study; but in 
noue of these were the methods adopted with the eggs 
sufficiently satisfactory in their results to enable me to do 
more at present than state that the general course of the 
development is the same in all these forms. Of the somewhat 
specialised New Zealand species — T. novim-zealandiae — I 
have procured ample material, which is now in course of 
preparation. 
AVhat has impressed me most strongly in connection with 
this investigation has been the complete absence in the 
development of any definite evidence of relationships with 
the groups looked upon as the most nearly allied. Until 
comparatively recently little that could be accepted as well 
authenticated had been published on the development either 
of the Rhabdocccles or of the Heterocotylean Trematodes. 
In the latter group as yet little has been done since the 
publication of Zeller’s (17) account of the development of 
Polystomnm in 1876. But Bresslau’s valuable work (3) 
has furnished us with a much-needed body of information on 
certain Rhabdocoeles, and this has enabled me to effect a 
comparison with Temnocephala, with the result that the 
differences appear to be more numerous and more radical 
than the resemblances. So far as can be ascertained in the 
present state of our knowledge, a similar result follows from 
a comparison with the Heterocotylean Trematodes. The 
upshot .seems to be that the study of the development, so far 
as it has been carried at present, does not in any way tend to 
