PE0E. OWEN ON A CAENIVOEOTJS EEPTILE. 101 



known and unsuspected as reptilian ones by zootomists, save through 

 the researches of the palaeontologist. 



T T the gap in the animal series between the Mesozoic and 

 r inianous air-breathers had not been filled up otherwise than by 

 reptiles, the remnant of that class which has survived and reached 

 our times would have testified to total loss of such gains of organiza- 

 tion as had enriched the ancestors or predecessors of modern 

 tortoises, lizards, and crocodiles. 



We now know that not one of these gains has been lost, but has 

 been handed on and advanced through a higher type of Yertebrata, 

 of which type we trace the dawn back to the period when Reptiles 

 were at their best, grandest in bulk, most numerous in individuals, 

 most varied in species, best endowed with kinds and powers of loco- 

 motion and with the instruments for obtaining and dealing with 

 food. 



Has the transference of structures from the reptilian to the 

 mammalian type been a seeming one, delusive, due to accidental 

 coincidence in animal species independently (thaumatogenously) 

 created ? or was the transference real, consequent on nomogeny or 

 the incoming of species by secondary law, the mode of operation of 

 which we have still to learn ? Certain it is that the lost reptilian 

 structures dealt with in the present paper are now manifested by 

 quadrupeds with a higher condition of cerebral, circulatory, respira- 

 tory and tegumentary systems, the acquisition of which is not 

 intelligible to the writer on either the Lamarckian or the Darwinian 

 hypothesis. 



EXPLANATION OF PLATE XI. 



Cynodraco major. 



Fig. 1. Nodule of Karoo clay-stone with fore part of skull, the upper canines 

 exposed (c, c). 



2. Side view of crown of right upper canine. 



3. Transverse section of ditto at the dotted line c, fig. 2. 



4. Portion of canine, magn. 2 diam., showing serrations of the trenchant 



hind border, c. 



5. Upper view of fore end of mandible, showing transverse sections of the 



crown-base of the incisors (i 1, 2, 3, 4) and canines (c'), with the 

 crowns of the upper canines (c, c). 



6. Front (thenal) view of left humerus, half natural size. 



7. Back (anconal) view of left humerus, half nat. size. 



8. Proximal end, abraded, of left humerus, half nat. size. 



9. Distal end, less abraded, of left humerus, half nat. size. 



10. Front (thenal) view of left humerus of Uromastix spinipes, nat. size. 



11. Back (anconal) view of left humerus of Uromastix spinipes, nat. size. 

 In the figures of the humerus, a, " head ; " b, ectotuberosity, here the be- 

 ginning of the delto-pectoral crest (b b') ; c, entotuberosity, not well defined ; d, 

 olecranal depression; e, beginning of "supinator ridge," ending at e, the 

 ectepicondyle (the ridge is less developed in Uromastix); f, entepicondylar 

 ridge ; /', entepicondyle ; I, ulnar condyle ; g, radial condyle ; h, bridge de- 

 fining Jc, the entepicondylar canal (fig. 6) ; on, bridge defining the ectepi- 

 condylar canal (figs. 10 and 11). All the figures of the natural size, save where 

 otherwise expressed. 



