Mr. T. Attlicy on Anthracosauru3 Ruaselli. 1 ">7 



are difficult of definition, owing to the cinished state of the 

 bones. 



At -^ inch behind the anterior margin of the bone there i.s an 

 oblique projection on eacli side of the middle line ; these are 

 ^ an inch apart at their anteinor, and l-i'^^ inch at their posterior 

 ends ; and each is y^ inch long. A well-defined smooth and 

 deep groove or channel runs along the inner sides of their 

 bases from before l)ackward.s. 



T/iC ba.'iiocrijn'tul is 2^ inches long by l.| broad at its posterior 

 part, and JL an inch at its apex. It is articulated in front to 

 the ba.^i.sphenoid, and on each side aj)parently to the quadrate 

 bone. The deep cavity behind for articulation to the body of 

 the first cervical vertebra is broken off obliquely near to its 

 posterior margin ; and the anterior part which remains is much 

 compressed. 



The occipiud surface is l-p-,7 inch in depth from the posterior 

 borders of the so-called supraoccipitals or top of the skull to 

 the lower border of the basiocci])ital. On the left side of the 

 median suture the bones are entire to near the outer margin 

 or angle of the exoccipital ; on the right side part of the ex- 

 occipital is broken obliquely off, together with a part of the 

 epiotic and basioccipital, exposing to view the sutures con- 

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

 supraoccipital is slightly overhung above and near to the 

 median hue by the so-called supraoccipitals of Von Meyer, 

 and next by a small portion of the epiotics : it is united below 

 to the occipitals ; but its outline is not clear. 



The exoccipitals, united to each other on the median line, 

 foraa the sides and upper margin of the foramen magnum. 

 They unite above, first to the supraoccipitals, 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 preseiwed, 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 right 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 posi- 

 tion to the right side of the cranium. 



The symphysis of the mandible measures only | inch in depth, 



