NEW LABYRINTHODONT AMPHIBIAN. 223 



immediately below and parallel to the belly. But it is impossible 

 to determine the exact length of this portion of the column, as 

 we cannot be sure how many of the anterior ribs are wanting. 



The ribs (e, e, e) are arranged in regular order, inclining from 

 before backwards, but have been apparently torn bodily from 

 their spinal attachment by pressure after deposition, and now 

 their proximal extremities are removed about an inch and a 

 quarter from the column, the whole having been afterwards 

 pushed downwards. Twenty-one are distinctly displayed in 

 parallel order, about a quarter of an inch apart from each other 

 in front ; but the space dividing the posterior ones is somewhat 

 greater. They are inclined diagonally from the front in slightly 

 arched curves, the concavity being forward ; and traces of eight 

 or ten more can be determined, so that in all there have been 

 about thirty ribs. In front, too, there are indistinct impressions 

 of one or two more ; but whether or not these terminate the 

 series in this direction it is impossible to say. 



The largest ribs, which are near the centre, are six inches and 

 a quarter in length, following the curve, and the shaft is one 

 quarter of an inch thick ; they taper slightly towards the distal 

 extremity, and do not exhibit the longitudinal groove or depres- 

 sion usually observed in the ribs of Labyrinthodonts, neither are 

 they apparently depressed in the usual manner. The proximal 

 extremities are crushed and broken, but are widened a little, in- 

 dicating a double articular surface ; these extremities are, how- 

 ever, too imperfect to warrant any confident assertion of the 

 fact. 



The greater number of the ribs have a crystalline appearance, 

 as if composed of a dark grey carbonate of lime ; but the con- 

 centric bone-layers are for the most part conspicuously displayed. 

 Eleven or twelve of the anterior ribs have more than an inch of 

 their distal extremity broken away, and the ruptured ends are 

 united to an irregular, narrow, thin, longitudinal belt of bone (/), 

 which is in the same crystalline condition as the ribs, and which 

 has a fanciful resemblance to a fragmentary breast-bone ; but 

 this appearance is altogether illusory, for, though this long belt 

 is completely incorporated with the extremities of the ribs, the 



