ME. T. ATTHEY OX AXTHEAC0SAT7RUS EESSELLT. 321 



epiotic and basioccipital, exposing to view the sutures connecting 

 these bones. The bone which I believe to be the true supra- 

 occipital is slightly overhung above and near to the median line 

 by the so-called supraoccipitals of Yon Meyer, and next by a 

 small portion of the epiotics : it is united below to the exoccipi- 

 tals, but its outline is not clear. 



Ihe exoccipitals, united to each other on the median line, form 

 the sides and upper margin of the foramen magnum. They 

 unite above, first to the supraoccipital, further out to the epiotics, 

 and below to the basioccipital. This forms the lower border 

 of the foramen magnum ; its lower border is broken off below, 

 as before noticed. 



The mandible. — Both rami are well preserved, and have been 

 separated from each other at the small loose symphysis, probably 

 in consequence of decomposition having been in an advanced 

 stage before the animal was finally enclosed in the mud and its 

 position fixed. 



The right ramus has been turned completely round, so that 

 its anterior end lies upon the posterior part of the light side, 

 and its posterior end upon the anterior part of the same side of 

 the cranium. 



The left ramus has also been moved from its normal position 

 to the right side of the cranium. 



The symphysis of the mandible measures only three-quarters 

 of an inch in depth, and nearly half an inch in breadth; it is 

 small in proportion to the size and strength of the jaw. 



The mandibular ramus of Anthracosaiirus consists of four ele- 

 ments, viz., the dentaiy, the articular, the angular, and the 

 splenial. 



First, the dentary, bearing the teeth, is long and narrow, 

 extending for nearly two-thirds of the length of the ramus ; its 

 anterior end, which is attenuated, forms one half of the sym- 

 physis ; its posterior, much broader, joins with the articular 

 piece ; by its inferior edge it articulates with the splenial poste- 

 riorly and with the angular anteriorly. Its surface is covered 

 all over with closely set and pointed tubercles. 



Second, the articular, the most massive piece of the ramus, is 



