33 



two. The cheeks form spherical triangles. The ocu- 

 liferous prominences are close to the second large 

 tubercle on the front. The cheeks are, however, 

 quite imperfect. The articulations of the back can- 

 not be distinguished from those of the tail. In our 

 specimen they are all beautifully distinct, and are 

 twenty-two in number. The posterior raised rim of 

 the buckler seems to form an articulation; its ex- 

 tremities on each side are a good deal thickened and 

 expanded. The costal arches suddenly curve down- 

 wards and backwards, near their middle, so as to di- 

 vide the abdomen and tail into five unequal sections. 

 The whole length is nearly three inches. The 

 breadth of the buckler nearly two inches. 



This fine large Calymene was accidentally disco- 

 vered on the Helderberg mountain, by my friend, 

 Professor T. R. Beck. One of the loose pieces of 

 sandstone rolling over, near his feet, presented him 

 the fine natural mould, from which he has kindly per- 

 mitted our cast to be taken. The animal relic once 

 enclosed in this matrix, must still be near that locali- 

 ty, and yet remains undiscovered, to reward the en- 

 terprise of some more fortunate naturalist. 



One of our models represents the natural mould 

 found by Dr. Beck. The other is a cast taken from 

 it and exhibits, more satisfactorily, the various parts 

 of the animal. 



