Yol. 63.] THE CRETACEOUS FORMATION OF BAHIA. 139 



Fig. 7. Macropoma Mantelli, Agass. ; portion of the left mandibular ramus, 

 outer aspect, showing articular {art.) and angular (ag.) bones, natural 

 size.— English Chalk. [Brit. Mus., No. P 6454.] 

 8. Ditto ; portion of the left mandibular ramus, outer aspect, showing 

 the meckelian ossification (m.) projecting beyond the angular bone 

 (ag.), and the quadrate (qu.) in position, natural size. [Brit. Mus., 

 No. 49094.] 

 [Unless otherwise stated, all the figures on Plates VII & VIII are drawn of 

 one-third the natural size.] 



Discussion. 



Mr. E. T. Netvton congratulated one of the two Authors on the 

 interesting and valuable material which he had collected, and the 

 other upon the admirable use which he had made of this material ; 

 especially in regard to the monster Coelacanth fish, the structure of 

 which had been so clearly pointed out to the Eellows present. 



Mr. Lydekker, after referring to the possible bearing of the 

 paper on the evolution of the Crocodilia and on continental 

 connexions and disconnexions, congratulated the Authors on the 

 result of their work. 



Mr. R. B. Newton, in thanking the Authors for their valuable 

 paper, stated that Mr. Mawson's collections contained some 

 interesting molluscan remains, among which were a number of 

 Anodont — or Unioniform — shells suggestive of Unio porrectus and 

 U. antiquus of British Wealden areas, associated with Vivijpara- 

 and Melania-like gasteropods, all of which had been studied by 

 Prof. Hartt and later by Dr. C. A. "White, both being of opinion 

 that they belonged to the Lower Cretaceous. The vertebrate 

 evidence now brought forward by Dr. A. S. Woodward, especially 

 the newly-recorded occurrence of Goniopholis, together with the 

 Lepidotus-sc&les originally determined by Egerton, was strong 

 confirmation as to the Lower Cretaceous age of these deposits. 

 Contrary to these views, it might be mentioned that Prof. A. de 

 Lapparent's ' Geologie ' contains a statement to the effect that the 

 fauna of these freshwater deposits of Bahia shows resemblances to 

 that which characterizes the Laramie Beds of North America. 



Dr. C. W. Andrews congratulated the Authors on the valuable 

 results that had been attained through the long and patient col- 

 lecting carried out by Mr. Mawson. He enquired whether any 

 crocodilian vertebras showing traces of a form intermediate between 

 the earlier amphiccelian and the later procoelian types had been 

 found, since it was about this horizon that the transition between 

 the two must have occurred. In fact, intermediate forms had 

 already been described in the vertebras of Goniopholid crocodiles 

 from the Lower Cretaceous in North America. 



Dr. Smith Woodward apologized for the absence of Mr. Mawson, 

 and briefly replied. The only vertebral centra that he had observed 

 which might be crocodilian were typically amphiccelous. 



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