162 FISHES—ORDERS OF 
anal fins are composed of soft rays only, there are at the anterior edge of the fin, from 
one to three undeveloped or rudimentary rays, usually closely adherent to the first 
developed ray. Some writers enumerate these in their descriptions, but in the present 
memoir they are not counted except in a few cases, where the fact is specitied. The 
short spines should, however, never be omitted. The last ray of the dorsal and anal 
fins is usually split to the base. This is counted as one not as two. | 
In certain fishes, as the Trout and Cat fish, there is on the median line of the back 
behind the dorsal fin a fleshy expansion known as the adipose fin, It has of course, no 
rays, and is not strictly a fin. 
In the present paper the number of spines is indicated by the use of Roman figures; - 
the number of soft rays, by Arabic figures. When a fin has both spines and soft rays, 
if the two kinds are united by a membrane, a comma (,) separates the number of spines 
from the number of soft rays. In case the spines are separated as a distinct fina 
dash (—) divides the two in the enumeration. Thus, in the Black Bass, ‘‘D. X,13” 
indicates a continuous dorsal fin, with ten spines and thirteen soft rays. In the White 
Bass, ‘‘ D. [IX—I,12” indicates two dorsals, whereof the first has nine spines, the second 
has one spine and twelve short rays. . 
The number of rays in the pectoral and caudal fins is seldom of any value in the classifi- 
cation of fishes. 
The abbreviations, D., dorsal fin; A., anal; C., caudal; P., pectoral; V., ventral; 
B., branchiostegals, and lat. 1., lateral line, are frequently used, especially in enumerat- 
ing the number of fin rays or scales. 
ARTIFICAL KEY TO THE ORDERS OF PISCES REPRESENTED IN OHIO. 
*Tail evidently heterocercal; ventral fins abdominal; no true spines, but some of the 
fins usually provided with falera, (Ganoidei). 
@. Skeleton cartilaginous; body naked or with series of bony bucklers. 
6b. Mouth narrow, inferior, toothless, preceded by four barbels. 
CHONDROSTEI, 3. 
bb, Mouth terminal, broad, with minute deciduous teeth ; snout prolonged into a 
spatulate process. : : 6 5 ° : SELACHOSTOMI. 2. 
aa. Skeleton bony; body scaly. | 
ce. Scales ganoid, 4. e. rhombic enamelled plates; dorsal fin short; no gular 
plates. 2 “ : . 6 5 6 5 GINGLYMODI. 4. 
ce. Scales cycloid; dorsal fin very long; a broad gular plate. 
| HALECOMORPHI. 5. 
**Tail not evidently heterocercal, ( Teleostei). 
d. Maxillaries wanting, or confluent with the palatines; body serpentiform; no 
ventral fins; vertical fins confluent, or nearly so around the tail. 
ENCHELYCEPHALI. 6. 
dd. Maxillaries present, rndimentary, each forming the base of a long barbel; no 
scales; dorsal and pectoral fins each with a single strong spine. 
NEMATOGNATHI 7. 
ddd. Maxillaries, complete, not forming the base of a long barbel. 
e. Ventral fins (in our species) composed each of a strong spine and a rudimen- 
tary ray; dorsal with free spines; body scaleless, naked or mailed. 
HEMIBRANCHII. 9. 
ee. Ventral fins if present, not as above. 6 5 : TELEOCEPHALI, 8. 
