JUEASSIC FAtJKA. 165 



ber of diminutive teeth implanted in sockets. But, on the "other 

 hand, the animal, which was of about the size of a rook, was pro- 

 vided with powerful wings, and these wings no longer consisted 

 simply of a tegumentary membrane, as in the case of the bats and 

 the extinct pterodactyls, but were made up of feathers as in living 

 birds, a character indicating that the animal provided with them 

 was warm-blooded. Feathers were also developed in pairs on 

 either side of the tail ; but the rest of the body, according to Vogt, 

 appears to have been completely naked. 



The mammalian remains of the Jurassic period consist princi- 

 pally of teeth and jaws, in a more or less complete state of pre- 

 servation, whose characters indicate animals of diminutive size, 

 pertaining wholly or in principal part to the order of the Marsu- 

 pialia, or pouched animals. Both the insectivorous and the her- 

 bivorous types had their representatives, the former in such genera 

 as Amphilestes, Phascolotherium, and Amphitherium, and the lat- 

 ter in Plagiaulax ; and it is not impossible that the more strictly 

 carnivorous type of marsupial also then existed. Stereognathus, 

 further, presents us with the type of a hoofed herbivore, and points 

 to a possible origin of the modern placental ungulata. Thus, the 

 marsupials had, as early as this period, attained a considerable de- 

 gree of differentiation, though apparently less considerable than 

 that exhibited by them at the present time. Latterly, some natu- 

 ralists, and notably Professor Marsh, have attempted to show that 

 these most ancient mammals of the Triassic and Jurassic periods 

 were not true marsupials, as these are now recognised, but that they 

 constitute distinct orders, Allotheria and Pantotheria, apart by 

 themselves ; there do not appear to be suflScient grounds, however, 

 for the separation here proposed. 



In the invertebrate fauna of this period we see, even more than 

 in the vertebrates, the reflection of the fauna of the period preced- 

 ing, but with the predominant features very largely extended. 

 These are in the main constituted by the moUusks, and more par- 

 ticularly by the cephalopoda, lamellibranchs, and gasteropods, the 

 brachiopods (Rhynchonella, Spiriferina, Terebratula, Terebratella), 

 although still sufficiently abundant, no longer having that para- 

 mount importance which distinguished them as perhaps the most 

 distinctive type of the Paleozoic faunas. The cephalopods still 

 belong, in the main, to the types of the nautilus, ammonite (Amal- 



