6 schlegel's gavial. 



We thus see that Mdriurhijnchus represents Uie most 

 f(eueralised conditiou, and that the recent Crocodilians, each 

 departing its own way from the primitive type, cannot be 

 arranged in a continuous series in this any more than in several 

 other parts of their structure. Whilst more generalised in 

 respect to the second rib* than the true Crocodiles, the Alligator 

 is more specialised in the more abei-rant position of the first rib, 

 and Avith the Alligator and Caiman in the strong bifurcation of 

 the second ; and Tomistoma and Osteolcemus present the highest 

 specialisation in the condition of the second rib with rudimentary 

 tuberciilum. 



P.S. (June 18, 1896).— Two days after the reading of my 

 paper I received Dr. Gadow's " Memoir on the Vertebral Column 

 of Amphibia and Amniota" (Phil. Trans, clxxxvii. B., pp. 1-57). 

 In this lie gives an account and a diagrammatic figure of the 

 atlas and axis of Metrinrhynclms, which differ entirely from what 

 I have observed. I at once re-examined the specimens, and 

 particularly that described by Hulke and figured by Dr. Gadow, 

 and find the latter statement to be erroneous. What is figured 

 as the first centrum is a portion of the first neural arch, the 

 posterior portion of which has passed on the figure into the 

 second vertebra; the tubercle (t), to which allusion is made, is 

 on the neural arch. 



• Another character in which the AUignfnr is more gener.alised than Caiman and 

 Crococltlns exists in the proatlas, the arches of which «re distinct, or shew at least 

 a trace of separation wliich is not to be found in tlie other genera, even in quite 

 young specimens. 



