58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 72 



scales which are in process of atrophy — on the way to disappearing. 

 A concurrent reason to regard them as scales is that traces of a 

 scaly covering are found in some extinct whales, Zcuglodon and 

 Dclphinopsis. 



But to Kiikenthal's and Abel's conception there is something to 

 oppose. 



It has been shown that the Hysenodonts, the most primitive car- 

 nivores, are the precursors of the Cetacea among terrestrial mammals. 

 Remains of Hysenodonts are found in great numbers in many locali- 

 ties ; but there has never been discovered the slightest indication that 

 any Hyasnodont or any other carnivore has been armored. Remains 

 of Zeuglodonts are found in various parts of the world, but nowhere 

 except in the case of the specimens from Alabama have dermal 

 ossicles been demonstrated in connection with the skeletons. If there 

 had been a dermal armature it certainly would have been found some- 

 where or other. Besides, it cannot be said to be proved that the 

 plates from Alabama are not those of some kind of turtle. Anyone 

 who has seen the roof-shaped keel on a Psephophorus carapace, and 

 has seen the fragments of the carapace mixed up together, will not 

 allow himself to be persuaded by Abel's word in this connection. 

 Finally it is improbable that Zeuglodon had a dorsal fin, since this 

 fin may be absent (probably not-developed rather 'than lost) in diverse 

 recent cetaceans, both Balsenids and Delphinids. 



The minute plates in Delphinopsis are altogether too uncertain to 

 give any evidence. Their characters are, besides, so far from recall- 

 ing what is otherwise known of dermal bones that one is tempted 

 rather to regard as an error their determination as such structures. 



The small callosities in the skin of. Neomeris and Phoccuna are 

 ■ scarcely the remains of a dermal armature, they are rather entirely 

 new structures. It is too suspicious that nothing of the sort should 

 be present in lower Cetacea, but that it should be in exactly some of 

 the very highest that it is found. The structure of the callosities, 

 moreover, gives no real support to the idea that they are scales. 



Altogether there is no proof that the Cetacea or their ancestors 

 among the mammals ever have had dermal armature. 



° (P. 10.) For comparison a few of the most important and most 

 independent synopses of the groups of Cetacea are here given. 



A fundamental work in the direction of throwing light on the 

 mutual relationships of the Cetacea is due to Flower, who, however, 

 took into consideration the recent forms only. In 1866 (69), in his 



