EASTMAN: CARBONIFEROUS SHARKS. 65 
restricted sense comprises four species from the Coal Measures of 
America, £. heinrichi,’ HE. minor, E. giganteus, and EH. vorax,— the 
last-named being the type; and a doubtful one from the European 
Carboniferous, — £. carbonarius (Germar). . minor and £. hein- 
richt also occur in the Russian Carboniferous, the latter having been 
described by Trautschold both as a distinct genus and species. Cam 
pyloprion includes three species, two of which, C. davisii? and C. lecontei ® 
were originally referred to Edestus, and the third, C. annectans, * is taken 
as the type. It need scarcely be remarked that all of the species here 
enumerated are known only by their symphysial dentition; many are 
founded on unique specimens, and the majority are in a more or less 
fragmentary state of preservation. Nevertheless these forms taken 
together constitute a remarkable series, in which the progress of evolu- 
tion is readily traceable. They signalize themselves as a group of 
Cestracionts, which early established the habit of retaining their worn 
symphysial teeth instead of shedding them. Later on, as these teeth 
became enlarged through specialization in various genera, the difficulty 
of accommodating them without their proving an encumbrance to the 
creature was overcome by the simple device of coiling, —the same 
mechanical contrivance which had already been carried to a remarkable 
perfection amongst Nautiloids, and was never afterwards abandoned 
amongst Ammonites except with disastrous or fatalresults. In this par- 
allelism between the coils of Helicoprion and involute Cephalopods we 
observe the culmination of efforts expended along a certain direction, the 
design being to accommodate a large number of segments in a minimum 
of space and at the same time to provide for a maximum rigidity. 
It remains for us now to describe the type-specimen of Campyloprion 
annectans, shown of two-thirds the natural size in Plate 4. The original 
was first brought to the writer’s attention by his friend Dr. J. S. Kingsley, 
of Tufts College, in whose custody it has been for many years. There is 
unfortunately no record of its history beyond the fact that it was origi- 
nally obtained for the Tufts Museum by the late Professor J. P. Marshall ; 
but as to either horizon or locality from which it was derived we are 
without information. No one can reasonably suppose, however, that the 
age of the fossil antedates the Coal Measures, or is younger than Permo- 
1 The commonly accepted orthography “ EF. heinrichsi,” is incorrect. Other 
instances of misspelled specific titles are Cladodus hertzeri pnd Dinichthys hertzert 
instead of C. and D. herzeri respectively. 
2 Woodward H., Geol. Mag. (8), Vol. III. (1886), p. 1, PI. i. 
3 Dean, B., eas. N. Y; Acad: Sct, Vol. XVI. (1897),'p: 62; Pl: iv. 
4 Eastman, C. R., Geol. Mag. (4), Vol. IX. (1902), p. 151. 
