COPE ON ICHTHYIC FAUNA OF THE GREEN RIVER SHALES. 813 
Caudal peduncle stout. The vertebra are contracted medially, and not 
shortened; they have two or three longitudinal keels, which are some- 
what irregular in their connections. This species is larger than any of 
the Erismatopteri yet known. 
wleasurements, 
: M, 
hength: fromfitst dorsal spine ssceusseee sore a2 saaseieaieecieans Seas eeeniesis 0.073 
Length from first anal spine......- 22. 02.20 eee cee eee cee nee cee ee cone ee cenees 0.051 
hengthsof anal Gis cox ee setwict Verein saseiee <seced wensieeiereans cieciies Senaeiestbe < 0.023 
Length of second dorsal spine... 2... eee. eee eee eee cee tee eee ce ceee eeneees vistas 0.015 
Length of third anal spine..........0.22..cceee ceeeee eee eee pie cena st ecreceer 0.013 
Depth at thirst anal spine iwcosetsweeek sds! cag gs cae semeud aeckee shee seem eeees 0.018 
ASINEOPS PAUCIRADIATUS, Cope, sp. nov. 
This Perch is represented by a single specimen, which is larger than 
any of those of the A. squamifrons, which have yet been found, and which 
is of more robust proportions. It differs materially in the radial and 
vertebral formule, and in the greater relative shortness of the dorsal 
spines. I observe at the base of these a series of short subhorizontal 
basilar interneural bones. 
Formule :—Radii: D. [X—12; A.II. 7. Vertebree: D. 9; C.13. One 
or two vertebre may be concealed behind the epiclavicle, but these, as 
in the description of A. squamifrons, are uncounted. The depth enters 
the length 2.25 times, the caudal fin being omitted. The length of the 
head is little less than the depth. The dorsal spines are not very ro- 
bust, and are (excepting the first) of subequal length. The longest 
equals only half the depth of the body at the middle of the second dor- 
sal fin. The caudal is rounded, and the ventrals are below the pectorals. 
The origin of the latter-is a little in advance of that of the first dorsal 
spine. Its base is attached to four short basilar bones, of which the 
inferior two are stout in proportions. There are about ten rows of 
eycloid scales below the vertebral column. Scales extend on the top of 
the head as far as the orbits. The mouth is terminal. The total length 
of the type-specimen is 0.243, of which the head constitutes 0.075. 
The longest (ninth) dorsal spine measures 0™.027, and the second anal 
spine 0™.024. 
MIOPLOSUS ABBREVIATUS, Cope, gen. et sp. nov. 
Char. gen.—Allied to Labrax and Perea. Branchiostegal rays, 7 or 8; 
yentral rays, I. 5.; scales ctenoid. Two dorsal fins slightly connected 
at base; only two anal spines. Operculum rounded, without spines or 
arnargination, Preoperculum without spine, and smooth on the posterior 
border ; inferior border with teeth. Premaxillary and dentary with small 
uniform teeth in a narrow series. Clavicle unarmed. Vertebrae with 
two lateral fossee. Caudal fin emarginate. 
The discovery of this genus in the Green River Shales is of no small 
importance to fossil ichthyology, proving the existence, at that early 
