Genera of Paralepididae — Harry 
229 
the form of the gillraker base, the loss of a 
cartilaginous sheath from the gillraker spines, 
and a progressive reduction in the length of 
these spines. There has been, however, an 
increase in the number of gillraker teeth. In 
Magnisudis there are 3-4, in Paralepis about 
5-10, and in Notolepis about 15-30 spines on 
each raker. In all three genera the spines are 
in two or more rows. 
All the rest of the genera in the family 
{Lestidium, Macroparalepis, Stemonosudis, and 
Sudis) have a singular form of gillraker and 
gillteeth which is also characteristic of the 
alepisauroid families Scopelarchidae, Everma- 
nellidae, Omosudidae, and Anotopteridae. It 
approaches most closely the condition in No- 
tolepis. The raker base is considerably reduced 
in size; the raker spines are very short, similar 
in form to those of Notolepis, but in a single 
row of 1-7 teeth. There is a tendency for 
the loss of gillrakers in Stemonosudis, as indi- 
cated by the fact that they appear to develop 
later than in other genera. 
The degree of similarity of the gillrakers 
between the varous genera is the same as the 
composite similarity of important characters 
and very likely expresses the degree of rela- 
tionship. If this hypothesis is true, we could 
expect on the basis of gillraker form that 
Magnisudis and Paralepis are more closely re- 
lated than either is to Notolepis. This state- 
ment is corroborated by many other charac- 
ters. For instance, the dentition of Magnisudis 
and Paralepis is strikingly reduced and tends 
to be completely absent in adults. The denti- 
tion of Notolepis, however, is well developed, 
not atrophied in adults, and approaches more 
closely the condition of Lestidium. This same 
balance of relationships is found in supra- 
maxillary form. The supramaxillary in Para- 
lepis and Magnisudis is strongly arched and 
widely separated from the maxillary except at 
its posterior insertion, but in Notolepis and all 
other paralepidid genera it is attached along 
its entire border to the maxillary. As a result, 
the genus Notolepis is an important link be- 
tween the scaled and naked genera; in most 
structures it is most closely related to Para- 
lepis and Magnisudis, but in some revealing 
characteristics it is the same as, or similar to, 
the naked genera, particularly Lestidium, 
Nevertheless, the genus Notolepis represents 
an end point, but in the line of scaled genera 
evolution. It has an extreme development of 
dentition (particularly in the subgenus Noto- 
lepis') and a unique form of lateral-line scales 
and tube not equaled elsewhere in the family. 
The genus is somewhat intermediate between 
Paralepis and Lestidium but the ancestral stock 
of the latter genus must have split off rather 
early from the Magnisudis-Paralepis-Notolepis 
stock. The sharpest break along the evolu- 
tionary line of the Paralepidinae as shown in 
Figure 4 is definitely between Notolepis and 
Lestidium, and the impressive differences of 
Magnisudis, Paralepis, and Notolepis (tribe Pa- 
ralepidini) from the scaleless genera (tribe 
Festidiini) within this subfamily have already 
been discussed. The scaleless genera of the 
family have very similar gillrakers, and, as 
would be expected, all of these genera are 
closely related on the basis of a large number 
of characters. 
Not all characters, however, follow as sim' 
pie an evolutionary pattern as the gillrakers. 
As has already been demonstrated, the lateral- 
line is a structure of considerable phylogenetic 
importance but has to be studied carefully 
because it can be highly variable even among 
individuals of the same species. In the Para- 
lepididae the simplest form of the lateral-line 
tube and scales is found in Magnisudis, where 
each segment has a single pore. In Paralepis 
there is usually the addition of a pore above 
and below in the tube, and in Notolepis there 
are numerous pores in each segment. The 
most complex pore patterns and lateral-line 
segment shapes are in the genus Lestidium, 
and there is finally the stabilization of pore 
number in Macroparalepis and Stemonosudis to 
two pores above and two below. While com- 
parison of lateral-line structure among the 
genera will show that the same degree of 
relationship exists between the various genera 
