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Palaeontological Laboratory of the University of Michigan, 

 under the direction of Prof. Alexander Winchell, to whom I am 

 indebted for much valuable assistance. I also wish to express 

 my obligation to Prof. D. S. Kellicott, of Buffalo, for the use of 

 specimens from his collection. 



GENUS PALAEONISCUS. DeBlainville. 



PALAEONISCUS RETICULATUS. (N. Sp.) Fig. 1, a. C. 



Bones of the head beautifully ornamented with prominent 

 raised lines which are nearly parallel, or reticulated (Fig. I, d.) 

 A fragment of bone has been found with ornamentation much 

 like the above, which seems to be one ramus of a mandible. It 

 is lanceolate in form, slightly curved, nearly one and one-fourth 

 inches long. It bears a few small conical teeth at each extremity, 

 with stumps of teeth near the middle. The surface is marked 

 by parallel lines, and shows traces of .reticulation. The scales 

 are mostly rhomboidal, contiguous sides about one-twelfth inch 

 in length. They are crossed by ridges parallel to the upper edge, 

 which are pointed behiind, forming serratures of the posterior 

 margin, and which anteriorly are many times multiplied in num- 

 ber, making spine-like serratures on the anterior margin. These 

 ridges interconnect or anastomose, giving thus a reticulated sur- 

 face (Fig. I, a.) Some scales are oval or nearly circular in form, 

 larger than the rhomboidal, but ornamented by similar ridges 

 (Fig. I, c.) Other structures have been found which seem to be 

 the scales placed over some portion of the dorsal line. They 

 are V-shaped plates about one-fourth inch long. The surface of 

 these is black and shining, ornamented by pits, or, along the in- 

 ner edges of the two branches, by pit-like indentations or 

 grooves, which are deepest and most numerous anteriorly. These 

 grooves separate ridges, which are directed obliquely forward 

 from the middle line of each branch, and which increase in num- 

 ber by implantation as they approach the edge, forming spine- 

 like serratures upon the inner margin (Fig. I, b.) The fin-rays 

 are represented by minute, oblong, flat bones, serrated on one 



