94 MONOGRAPH OF THE FRESH WATER II. 
the latter into the nasal cavity, thus meeting the suborbital branch on the snout. 
The supraorbital we were at a loss to find. 
The hyoidean apparatus is composed of the usual bones. The small stylohyal 
(38) is nearly straight; the epihyal (39) subtriangular, bearing two branchiostegals. 
The ceratohyal (40) is the longest, and attached to it are the four remaining branchi- 
ostegals. The basihyal and glossohyal are seen, one in front, the other above the 
anterior extremity of the ceratohyal. The uwrohyal (43) is provided with an elon- 
gated membranous appendage underneath. The branchiostegals (44) are cylindrical 
and slightly curved. 
In the branchial arches, the small basibranchials (45) are scarcely to be distin- 
guished, this series of bones forming a cartilaginous band in the midst of which 
minute surfaces of ossification alone are discernible. The hypobranchials (46) are 
independent from each other, short, thin, and flattened, varying somewhat in shape. 
The ceratobranchials (47) are very slender, slightly convex, provided on both sides 
and inwardly with little tubercles beset with extremely minute teeth. The epi- 
branchials (48) are the most variable of all the bones constituting an homonyme 
series. The pharyngobranchial (49) is subquadrangular, the entire exposed surface 
of which is covered with minute teeth. The inferior pharyngobranchials (49') are 
elliptical and beset with teeth similar to those of the pharyngobranchials. 
The suprascupular (50) is as usual, situated above the paroccipito-mastoid groove; 
but its centre is hollow. The scapular (51) is subtriangular, thin and flat. The 
coracoid (52) is likewise very thin, flattened upon different planes, and crescentic. 
The epicoracoid (58) is styliform and a little longer than represented on the figure. 
The wna (54), the radius (55), and the carpals (56), are altogether in a cartilagi- 
nous state. The ulna and radius are contiguous and form a band along the cora- 
coid, thus preventing the carpals from coming into contact with the latter. The 
carpals themselves are surrounded by a thin semi-membranous edge, on which the 
metacarpophalangeals (57) articulate. 
The ventral fins are connected with the lower part of the scapular arch. The 
pubic bones (63) are subtriangular, furnishing posteriorly a point of attachment to 
the metatarsophalangeals (70). The external and shorter one is bony and unjointed, 
whilst the three remaining ones are soft and jointed. 
The vertebral column is composed of thirty-nine vertebra, twelve of which 
belong to the abdominal region, and twenty-seven to the caudal. Accordingly, 
there are twelve pairs of ribs corresponding to the twelve abdominal vertebra, 
three of them being provided with pelvic appendages. The centrum is circular; 
the vertical diameter of the middle of the body of the vertebra, however, is greater 
than the transverse. The neurapophyses and hemapophyses generally are quite 
uniform, slender, and little prominent. The neural spines (7 s) are scarcely apparent 
on the anterior thoracic vertebra (1, 2). The same enlarged figures exhibit the 
peculiar shape of the neural arch seen from behind (1) and in profile (2), together 
with the insertion of the ribs (p/). The numbers 1 to 12 appended to the verte- 
bree do not indicate their rank in the series. Numbers 3 to 12 are of natural size, 
and were intended to illustrate their special structure all along the column; but 
the figures are altogether too small. Numbers 1, 2 and 3 belong to the thoracic 
