278 NATURAL. SCIENCE. APRIL, 
method of development, yet not the most sanguine of them will hope 
to find so perfect an epitome of phylogeny in the majority of cases. 
The necessary compression, the constant elimination of unnecessary 
stages, the modifications required by larval conditions—all these things 
make it truly remarkable that we should get as much recapitulation 
as we do. Yes, we do get it, and this is ‘‘the way in which it does 
actually occur,” let Mr. Hurst deny it as much ashe pleases. In fact, 
no more perfect example of this impossible and non-existent method 
of development could be imagined than that which is actually afforded 
us by the paleontological history of the Ammonites. Does Mr. Hurst 
dispute the reality of the facts made known to us by Wirtenberger, 
Waagen, Branco, Hyatt, Buckman, and many others ? Not everyone 
will accept the alterations in classification proposed by these workers,, 
but no one has hitherto been found to deny their facts. The reason 
why no one has done so is obvious: anyone can verify them for him- 
self. It has been shown over and over again, by workers approaching 
the subject quite independently and from different points of view, that 
the adolescent stage of any species of Ammonite resembles the adult 
stage of its immediate ancestor, and that the larval stage resembles. 
the adult of a previous ancestor ; while, on the other hand, the senile 
stages of the same species foreshadow the features of the adult 
offspring. These facts have not merely been worked out by students 
in museums, by dissection of well-preserved individuals, and com- 
parison of large quantities of specimens, but have been confirmed by 
minute labours in the rocks themselves, and by the careful tracing of 
the species from zone to zone over large tracts of country. 
A suitable example is presented by the descent of Coroniceras 
trigonatum from a smooth ancestor, as indicated in Hyatt’s ‘‘ Genesis 
of the Arietide,’’ Summary-plate xii. Hyatt here gives the ancestry 
as follows:—C. trigonatum, C. gmuendense, C. lyva, C. rotiforme, 
C. sauzeanum, C. kridion, Ayrnioceras kyridioides, A. semicostatum, and 
Psilocevas planorbe, var. leve. .To obtain an independent opinion, I 
applied to my friend, Mr. S. S. Buckman, who informs me that he 
agrees with the first six names except as to the interposition of 
C. sauzeanum. He, however, ‘ would not like to say that the species 
of Avnioceras are the actual ancestors ; but they are the morphological 
equivalents undoubtedly of those ancestors.’’ There is also consider- 
able objection to taking a retrogressive type like Psiloceras planorbe as 
the starting point of a newseries. At the same time, even those who. 
refuse to regard this particular species in the same light as Professor 
Hyatt, will admit that the ancestor must have been a somewhat 
similar smooth, keelless, and round-sectioned form; in fact, Buckman 
favours Aynioceras miserabile, which Hyatt himself gives as an 
ancestral form. Accepting, then, this line of descent, we may draw 
up the accompanying table, which traces the development of three 
main characters in both ontogeny and phylogeny. The first column 
describes the infantine. stage, the second the adolescent, and the 
