82 



Among these the genus Palaeoniscus is represented by small, 

 black rhomboidal scales, and fragments of bone, which belong 

 to two different species. These species I have named Palaeonis- 

 cus reticulalus, and Palaeoniscus antiquus. Besides these there are 

 other scales, belonging to at least three different genera, but so 

 far not determined. I have also two plates, which plainly are 

 part of the armor of some Placoderm. In their surface mark- 

 ings they resemble Mr. Ringueberg's figure of Dinichthys minor, 

 but their outlines are too indistinct to determine to what part of 

 the body they might have belonged. It is to be hoped that fur- 

 ther investigation may throw more light on these interesting 

 fossils. 



There are also certain remains of a doubtful character which 

 must at least be mentioned. These are what are known as Con- 

 odonts. They are nearly microscopic, tooth-like bodies, which 

 have been found in strata ranging from the lower Silurian to the 

 Carboniferous, both in Europe and America. They are consid- 

 ered by some authorities as spines of Mollusks, by others as 

 belonging to Crustaceans, and by others still as the jaws of 

 low varieties of fishes. This last opinion has a particular inter- 

 est on account of the vast antiquity such a supposition would in- 

 volve for the Silurian specimens. One of the most fruitful lo- 

 calities in America for Conodonts has been the exposure of the 

 Hamilton and Genesee shales on Lake Erie, south of Eighteen 

 Mile Creek. Descriptions and figures of a large number of 

 forms from this place are given in the Quarterly Journal of the 

 London Geological Society for 1879, by Dr. Hinde. I have 

 found similar specimens in the Portage group as well, at Stur- 

 geon Point and elsewhere. They are plainly visible under a 

 low magnifying power, being white and nearly translucent. 

 They consist of single teeth, or rows of teeth, upon a base, with 

 which they are coalescent, and sometimes they are not unlike a 

 comb in appearance. 



Below are given descriptions of the two species of Palaeoniscus 

 before mentioned. The work which the description of these 

 specimens has involved, I have performed while studying in the 



