162 report — 1859. 



of the trunk are long and curved, the anterior ones having bifurcate heads : 

 there is a sacrum of four or five vertebra?, forming, with broad iliac and pubic 

 bones, a large pelvis. Limbs ambulatory. 



Family Dicynodontia *. 

 A long ever-growing tusk in each maxillary bone : premaxillaries connate 

 and forming with the lower jaw a beak-shaped mouth, probably sheathed 

 with horn. This family includes two genera, Dicynodon and Ptychognallms, 

 all the known species of which are founded on fossils from rocks of probably 

 triassic age in South Africa. 



Family Cryptodontiaj- . 



Upper as well as lower jaw edentulous. The genus Ondenodon closely 

 conforms to the Dicynodont type, and the species are from the same rocks 

 and localities. 



Family Gnuthodontia\. 



Two curved tusk-shaped bodies holding the place of the premaxillaries, 

 and consisting of confluent dentinal and osseous substance, descending in 

 front of the 'symphysis mandibular' These bodies are homologous with the 

 pair of confluent premaxillary teeth and bones in the existing New Zealand 

 amphiccelian lizard Rhynchocephalus ; they are analogous to the tusks in the 

 Dicynodonts, and must have served a similar purpose in the extinct reptiles 

 (Rhynchoscmrus) of the New Red (Trias) Sandstone of Shropshire, in which 

 alone, this structure, with an otheiwi.se edentulous beak-shaped mouth, has 

 hitherto been met with. The Rhynchosauroid reptile from the sandstone of 

 Lossiemouth, near Elgin, is described by the Professor in the Government 

 School of Mines, as having palatal teeth ; but its close affinity to tiie Rhyn- 

 chosaur of Shropshire adds to the probability of the triassic age of the Los- 

 siemouth sandstone. 



Order VI. Pterosauiua§. 



Although some members of the preceding order resembled birds in the 

 shape or the edentulous state of the mouth, the reptiles of the present order 

 make a closer approach to the feathered class in the texture and pneumatic 

 character of most of the bones, and in the modification of the pectoral limbs 

 for the function of flight. This is due to the elongation of the antibrachial 

 bones, and more especially to the still greater length of the metacarpal and 

 phalangial bones of the fifth or outermost digit, the last phalanx of which 

 terminates in a point. The other fingers were of more ordinary length and 

 size, and were terminated by claws, .the number of their phalanges progressively 

 increasing to the fourth, which had four joints The whole osseous system 

 is modified in accordance with the, possession of wings: the bones are light, 

 hollow, most of them permeated by air-cells, with thin, compact outer walls. 

 The scapula and coracoid are long and narrow, but strong. The vertebra? 

 of the neck are few, but large and strong, for the support of a large head 

 with long jaws, armed with sharp-pointed teeth. The skull was lightened 

 by large vacuities, of which one was interposed between the nostril and the 

 orbit. The vertebra? of the back are small, as are those of the sacrum, 

 which were from two to five in number, but combined with a small pelvis 

 and weak hind limbs, bespeaking a creature unable to stand and walk like a 

 bird : the body must have been dragged along the ground like that of a bat. 

 The vertebral bodies were united by ball-and-socket joints, the cup being 



* Sis, twice ; Kvvodovs, canine-tooth. t KpvTrrbs, concealed ; oSovs, tooth. 



% yvdBos, jaw; ddois, tooth, § irrepbv, wing ; aadpos, lizard. 



