10 PROFESSOR A. M. MARSHALL. 



and more seriously studied by men versed in embryology, and that 

 those who have so greatly advanced our knowledge of the early 

 development of animals should so seldom have tested their conclusions 

 as to the affinities of the groups they are concerned with by direct 

 reference to the ancestors themselves, as known to us through their 

 fossil remains. 



I cannot but feel that, for instance, the determination of the 

 affinities of fossil Mammalia, of which such an extraordinary number 

 and variety of forms are now known to us, would be greatly facilitated 

 by a thorough and exact knowledge of the development, and especially 

 the later development, of the skeleton in their existing descendants, 

 and I regard it as a reproach that such exact descriptions of the later 

 stages of development should not exist even in the case of our 

 commonest domestic animals. 



The pedigree of the horse has attracted great attention, and has 

 been worked at most assiduously, and we are now, largely owing to the 

 labours of American palaeontologists, able to refer to a series of fossil 

 forms commencing in the lowest Eocene beds, and extending upwards 

 to the most recent deposits, which show a complete gradation from a more 

 generalised mammalian type to the highly specialised condition 

 characteristic of the horse and its allies, and which may reasonably be 

 regarded as indicating the actual line of descent of the horse. In this 

 particular case, more frequently cited than any other, the evidence is 

 entirely palseontological. The actual development of the horse has yet 

 to be studied, and it is greatly to be desired that it should be uuder- 

 taken speedily. Klever's l recent work on the development of the 

 teeth in the horse may be referred to as showing that important and 

 unexpected evidence is to be obtained in this way. 



A brilliant exception to the statement just made as to the want of 

 exact knowledge of the later development of the more highly organised 

 animals is afforded by the splendid labours of Professor Kitchen 

 Parker, whose recent death has deprived zoology of one of her most 

 earnest and single-minded students, and zoologists, young and old 

 alike, of a true and sincere friend. Professor Parker's extraordinarily 

 minute and painstaking investigations into the development of the 

 vertebrate skull rank among the most remarkable of modern zootomical 



1 Klever, ' Zur Kenntniss der Morphogenese des Equidengebisses,' 

 MorpKologisches Jahrbuch xv. 1889, p. 308. 



