EXTINCT BATRACHIA. 411 



the other concave. The latter is more ovoid, broad, and convex next the 

 first mentioned, and somewhat more contracted at the opposite extrem- 

 ity. Beyond this are two shields joining by a straight suture on the 

 middle line. Besides this one, they have two concave sutures for scuta at 

 the farther end, two concave lateral sutures, and a straight one to the 

 adjoining median scutum, whose suture is also concave. On each side of 

 this median plate is a large area, surrounded before, outwards, and be- 

 hind by smaller scuta— three in front, two at the side, and two behind. 

 Commencing with the first. No. 1 has been already described ; No. 2 is 

 small, oval, and antero-posterior; No. 3 is an antero-posterior pentagon, 

 with the narrowest side inwards ; No. 4 is a similar transverse pentagon; 

 No. 5 is an antero-posterior pentagon, which presents its shorter lateral 

 facet inwards ; No. 6 has a similar character, but is smaller, and with 

 more definite angles. Another series of scuta is seen outside of these at 

 one end of the series. Three of this set bound the front and side of each 

 of the median pair above mentioned, leaving a short facet next its fellow 

 unaccounted for. 



The sculpture consists of radiating ridges and tubercles, which are 

 most broken near the centers of the scuta. 



The pits and grooves of the cranium are obtuse and shallow, and the 

 latter do not inosculate. An angular elevation commences at the mid- 

 dle of each central area, and extends across the middle line at the point 

 of junction of the paired and single median scuta. 



The specimen above described accompanied the jaws of the Leptophrac- 

 tus obsoletus, and were so marked as to induce the belief that they were 

 found together. It was, therefore, originally described in connection 

 with that species, but was afterwards assigned to its present position. 



