CONTRIBUTIONS TO THE MORPHOLOGY OF 
CLADOSELACHE (Cladodus). 
BASHFORD DEAN, 
Cotumsta COLLEGE, New York City. 
UNTIL very recent times the Morphology of Elasmobranchs 
has received few contributions from the study of the earlier 
fossilforms. It was, in fact, hardly to be expected that uncalcified 
shark structures should have preserved with any completeness 
the record of their ancient characters. Fragmentary remains 
on the other hand have, in many cases, led to confused and 
contradictory results. It was not until 1888! that accounts, in 
any way satisfactory, were given of the chief features of 
palaeozoic sharks. In this year there appeared almost simul- 
taneously, a description of the Carboniferous Pleuracanthus by 
Brongniart,! of the Lower Carboniferous Chondrenchelys and 
Cladodus (pectoral fin) by Traquair,?, 14, of a Cladodont shark 
from the Ohio Waverly by Newberry,3 and of the pectoral fin 
of Xenacanthus by Fritsch.4 Subsequent papers of especial 
importance morphologically were contributed by Fritsch,5; 6 
Déderlein,7 Smith Woodward,’ 9 Newberry,1° Wiedersheim!! 
and Jaekel.12, 13 
The sharks discussed at that time by Newberry were received 
from Rev. Dr. William Kepler of New London, Ohio. They 
had been collected at Linton, and represented the remains 
of about six individuals. The remarkable characters they 
exhibited proved in no small degree puzzling to their describer. 
The dentition was undoubtedly Cladodont and the name 
Cladodus was retained, although it was clearly recognized that 
a number of genera and even families might be represented 
by this generalized type of dentition, and that a new genus 
might be assigned when more material of the type (Cladodus 
mirabilis) should be found. Whether the partial description 
1 The writer must here except the memoir of Cope’ on Didymodus and the 
earlier studies of Acanthodians. 
