1894. NOTES AND COMMENTS. 175 



ledge of the whales of old time is rapidly increasing. Palaeontolo- 

 gists have recently been exercised to some extent regarding the 

 affinities of those remarkable gigantic Eocene mammals known as 

 Zeuglodonts, the remains of which have now been discovered in so 

 many parts of the world. Till a short time ago, these animals were 

 pretty generally admitted to be members of the Cetacean order, in 

 which they were regarded as constituting a separate subordinal group 

 — the Arch aoceti. In a memoir pubhshed in the " Studies from the 

 Dundee Museum" for 1890, Professor D'Arcy Thompson took, 

 however, a decided exception to this view, maintaining that the 

 Zeuglodonts had nothing whatever to do with whales, but that their 

 affinities lay rather with the seals. Two years later, Mr. Lydekker, 

 when describing in the Proc. Zool. Soc, some Zeuglodont remains from 

 the Caucasus, again discussed the question, and came to the conclu- 

 sions that there was no justification for the proposed innovation, and 

 that the Cetacean nature of the group in question was undoubted. 



In a recent communication {Palaontologische Abhandliingen, ser. 2, 

 vol. i., pt. 5, 1893), Professor Dames has " gone one better " than this, 

 concluding that not only should the Zeuglodonts be classed among 

 the Cetacea, but that there are no grounds for separating them as a 

 distinct suborder from the Odontoceti. He accordingly proposes the 

 following scheme of classification for the latter order : — 



1. Arch.^oceti ; — teeth few and differentiated. (Zeuglodontidae.) 



2. Mesoceti ; — teeth numerous and differentiated. (Squalodontidae.) 



(Platanistidae. 

 Delphinidae. 

 Physeteridae. 



In the resemblance presented by their skulls to ordinary terrestrial 

 mammals, coupled with the small number of their teeth, the 

 Zeuglodonts are sharply defined from the Squalodonts, and thus 

 form the most primitive of all Cetaceans. The Squalodonts appear, 

 however, on the whole, to occupy an intermediate position between 

 the Zeuglodonts and Delphinoids, and thus serve to connect the three 

 groups of toothed whales. 



Not the least noteworthy portion of the Professor's memoir is the 

 one in which he describes certain bony plates found in association with 

 Zeuglodont remains, which are believed to indicate the presence of a 

 dorsal bony dermal armour. That such an armour may have 

 existed in primitive Cetaceans, is rendered the more probable by Dr. 

 Kukenthal's recent discovery of the vestiges of such a structure in 

 the skin of the existing Phoccena {Neomeris) phoccenoides. 



Possibly the ancient Cetaceans were more exposed to such 

 attacks as the one above described by Mr. Lydekker, and, for this 

 reason, required greater protection. It is well known that the early 

 forms of many groups of animals were provided with some such 

 armour, or evolved some equally adequate means of defence. As 



