VERTEBRATES. 141 



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nearly double the size, and having relatively longer and stronger anterior limbs. 

 The angles of the mandible appear to have been considerably more incurved 

 than in the Illinois species. They may have belonged to the same genus; in 

 that case the name here given will not prove superfluous, as the older appella- 

 tion was previously applied to a genus of Gadid fishes. 



The name Amphibamus grandiceps has reference, first, to its two modes of 

 progression ; its flattened oar-like tail enabled it to swim in the waters of the 

 swamps of the coal period, and its elongate, clawed digits indicate ambulatory 

 power; perhaps it climbed upon the low limbs of the Sigittarise that rose above 

 the water. The animal was most probably nocturnal in its habits. The humors 

 of the eye could not have escaped far beyond their natural envelopes, so that 

 the subsequently formed limestone has been hardened, and so fractured in 

 nearly the form of the ball. On the fractured surface, below and under the 

 remaining palpebral scales, the mineral is distinctly blackened, as by the pig- 

 mentum nigrum; below the margin of the lid thi3 is interrupted by a discoid 

 spot of the form and dimensions of an iris, which presents a median lenticular 

 vacuity, again revealing the pigment, obviously the vertical pupil of a nocturnal 

 animal. The preservation of the outline of color is certainly remarkable in a 

 specimen of such great antiquity. A somewhat parallel case occurs in the 

 preservation of the ink-bags of the Sepise; but these do not date further back 

 than the Jurassic. These appearances can not be explained on any supposition 

 of accidental production. 



