220 DR. H. GADOW ON THE EVOLUTION [Mar. 18, 



renewal of the haiiy coat is likewise repeated by the hoiny 

 sheath. This stage is still represented by Antilocapra, 

 although the horny sheath by continued basal growth 

 gradually envelops also the greater part of the pedicle, 

 (Text-fig. 25, III, p. 216.) 

 IV. Direct continuation of types II and III, still repeated 

 stage by stage ontogenetically. An improvement towards 

 the preponderance of the intercrinal horn- substance, the 

 conversion of the sheath into a morphologically well- 

 finished horn-sheath, the suppression of the hairs, and of 

 periodical shedding of any part of the whole compound 

 weapon, was only a question of time with onward evolution, 

 This, the highest and most perfect stage, is represented by 

 the typical Antelopine or Bovine Ruminants, of which 

 their peculiar member, the Prongbuck, still falls short. 

 They are morphologically the highest, palaeontologically 

 the latest of Ruminants. Herewith it agrees that horns 

 are carried by both sexes, whilst the inheritance of these 

 organs by the females is still a rare exception amongst the 

 Cervince. Moreover, these weapons, having become per- 

 manent and evergrowing, and therefore useful throughout 

 the year, are of much greater value to their bearers. 

 (Text-fig. 25, TV, p. 216.) 



Attention has already been drawn in this paper to the important 

 fact that the horns of a young calf still contain a considerable 

 number of hairs mixed up in the sheath, and that in older 

 animals such hairs are restricted to the more basal portions ; 

 secondly, that the top cone of the hornshoe is shed. In Ewes 

 this first generation falls ofi" as a thin, transparent cap of the 

 size and shape of half a hazel-nut. In fact this first cap of the 

 Bovine horn is in every respect homologous with the shedding 

 sheath of the Prongbuck. The Oxen, Sheep, and Goats now 

 -exhibit only once a process of shedding which in their immediate 

 ancestors must have been of frequent occurrence, and which in 

 the Prongbuck is still a periodical feature. 



The types I, II, III, and IV, exemplified by the Eocene 

 Dinoceras, the Cervince since the Lower Miocene, the Prongbuck, 

 still existing, and the hollow-horned Ruminants or Bovince, are 

 an illustration of onward phyletic evolution ; and these stages 

 ai'e still faithfully repeated in the development of the recent 

 species. Ontogeny is a shortened recapitulation of phylogeny. 



Titles of the mm^e important Literature referred to in the text. 



Sandifort, G. Over de Vorming en Ontwikkeling der Horens 

 van zogende dieren in het algemeen en van die der Herten- 

 beesten in het bijzonder. Nieuwe Verhandl. i. Klasse 

 Koningl. Nederl. Inst. Wetenschap. ii. (1829). pp. 67-106; 

 wiih 7 jjlates. > 



