352 PALAEONTOLOGY AND EVOLUTION xi 



articular surfaces for the free jointing of the 

 bones of the fore-arm. In the apparently com- 

 plete absence of hinder limbs, and in the characters 

 of the vertebral column, the Zeuglodon lies on the 

 cetacean side of the boundary line ; so that upon 

 the whole, the Zeuglodonts, transitional as they 

 are, are conveniently retained in the cetacean 

 order. And the publication, in 1864, of H. Van 

 Beneden's memoir on the Miocene and Pliocene 

 Squalodon, furnished much better means than 

 anatomists previously possessed of fitting in 

 another link of the chain which connects the 

 existing Cetacea with Zeuglodon. The teeth are 

 much more numerous, although the molars exhibit 

 the zeuglodont double fang ; the nasal bones are 

 very short, and the upper surface of the rostrum 

 presents the groove, filled up during life by the 

 prolongation of the ethmoidal cartilage, which is 

 so characteristic of the majority of the Cetacea. 



It appears to me that, just as among the 

 existing Carnivora, the walruses and the eared 

 seals are intercalary forms between the fissipede 

 Carnivora and the ordinary seals, so the Zeuglo- 

 donts are intercalary between the Carnivora, as a 

 whole, and the Cetacea. Whether the Zeuglodonts 

 are also linear types in their relation to these two 

 groups cannot be ascertained, until we have more 

 definite knowledge than we possess at present, 

 respecting the relations in time of the Carnivora 

 and Cctacea. 



