PLATE XV. 



Dorsal portion of the carapace, with cranial shield, of Asterolepis maxima, 

 Agassiz, sp., seen from the interior ; one-fifth smaller than the original. 

 This is the best specimen, with plates in apposition, which ever has been 

 found; unfortunately the arms are wanting, and the cranial shield and 

 posterior dorso-lateral plate are somewhat injured on the left side. The 

 natural mould or counterpart of this specimen, not figured, gives an 

 excellent idea of the general proportions of the creature, but the plates on 

 the ventral surface are very badly preserved (for the letters p. a. I. on the 

 shield read p. d. I.). 



