FISHES OF THE CARBONIFEROUS SYSTEM. File 
scorpions, spiders, cockroaches, or fishes. Among the latter are three 
species of Paleoniscus, one of Amblypterus, and two of Platysomus, which are 
described in the Paleontology of Illinois. Large ornamented scales of two 
or three kinds are also occasionally met with in the iron-ore nodules; they 
have been referred to Rhizodus, but it is not at all certain that they belong 
to that genus. Since the notice of the Mazon Creek fishes was published 
in the report of the Illinois Geological Survey I have received from there a 
single specimen each of Eurylepis and Calacanthus, probably not distinct 
from those found at Linton. 
In the shales of the Coal Measures at Belleville and Carlinville, IL, 
Mr. Alexander Butters has collected a large number of fish remains; these 
consist mainly of the teeth of Cladodus, Petalodus, Sandalodus, Orthopleurodus, 
and the spines of Edestus. The latter all belong to the species L. Heinrichsi, 
N. & W., and are often disarticulated in such a manner as to show distinetly 
the structure and mode of growth of this singular organ. These I have 
illustrated with figures in another part of this memoir, and I will only say 
here that in this species, as well as in E. minor, which I have from the Coal 
Measures of Indiana, growth took place by additions of sheaths to the 
upper extremity of the first segment. This proves that the spine was all 
buried in the integument except the great compressed, enameled, crenu- 
lated denticles; each of which was borne at the extremity of its own 
segment or sheath. The spine is symmetrical, and therefore was placed 
on the median line, probably near the tail, where considerable freedom 
of motion would permit its being used to lacerate any attacking foe. I 
have suggested that it was carried far back on the dorsal line like the spines 
of Trygon. 
Ihave included Megalichthys in the list of American Coal Measure 
fishes, because I have found in Ohio masses of scales and bones which are 
scarcely distinguishable from those of Megalichthys Hibberti, Ag These 
are rhomboidal in outline, hal. am inch to an inch in length; the surface 
covered with brown, highly polished, punctate enamel. ‘They occur in a 
black shale over a bed of coal at Mineral Point, Stark County, Ohio, in cir- 
cumstances similar to those in which the remains of Megalichthys are found 
in England. 
