262 
PACIFIC SCIENCE, Vol. IX, July, 1955 
TABLE 1 
The Number of Individuals of Plesiops corallicola with Different Numbers of Branches in the First, 
Fourth, and Sixth Pectoral Rays (The Rays are Counted from the Ventral Margin of the Fin) 
NUMBER OF BRANCHES 
OF SPECIMENS 
First ray 
Fourth ray 
Sixth ray 
2 
3 
4 
over 4 
2 
3 
4 
5 
6 
7 
over 7 
2 
3 
4 
5 
6 
7 
over 7 
Under 40 mm 
4 
3 
1 
2 
2 
2 
2 
40-49 mm 
2 
5 
2 
4 
2 
4 
1 
50-69 mm 
1 
11 
2 
1 
3 
1 
1 
1 
3 
2 
70 mm. and up 
9 
18 
5 
2 
6 
4 
6 
3 
The sub-totals exhibit a tendency toward 
an increase in the number of branches with 
increase in size. This conclusion is borne out 
by applying a chi-square test to the sub-totals. 
The results of the test (chi-square = 11.84; 
n = 4; P = 0.02) show clearly that the dis- 
tribution within the table is not at random. 
If, as seems evident from the data presented, 
the extent to which the lower pectoral rays 
are divided is dependent on size within spe- 
cies, the difference between the three small 
species on the one hand and the three large 
ones on the other in this character is probably 
a function of the differences in size at ma- 
turity. 
KEY TO SPECIES OF PlesiopS 
The following key, which has been made 
simple in order to facilitate its use, should 
permit identification of about ninety per cent 
of all specimens. The exceptional individuals 
can be identified by comparison with the 
diagnoses appearing just before the descrip- 
tion of each species. 
lA. Dorsal spines usually XII; total gill 
rakers usually more than 13 . . . 2 
B. Dorsal spines usually XI; total gill 
rakers usually 13 or fewer . 
coeruleolineatus Riippell 
2A. A dark ocellus on opercle; ocellus sep- 
arated from post-orbital black bars 
corallicola Bleeker 
B. A black stripe continuous from eye to 
end of opercle, or opercle without any 
black mark 3 
3A. Four lowest pectoral rays with one or 
two branches each 4 
B. Four lowest pectoral rays with more than 
two branches each, usually with four or 
more branches .5 
4A. Caudal with a broad, crescentic orange 
(pale yellowish in preserved fishes) 
band, bordered peripherally by a narrower 
black band; no post-orbital black bar 
crossing preopercle. 
. oxycephalus Bleeker 
B. Caudal uniformly black or with a light 
margin; middle post-orbital bar crossing 
preopercle. . cephalotaenia new species 
5 A. Upper lateral line with 25-30 scales; 
mid-lateral scales 28-34. 
multisquamata new species 
B. Upper lateral line with 19-23 scales; 
mid-lateral series 23-27 
nigricans Riippell 
Plesiops nigricans Riippell 
Fig. 3 d 
Pharopteryx nigricans Riippell, 1828, Atlas 
Reise nordl. Afrika, Fische, p. 15, ph 4, 
fig. 2— Mohila, Red Sea. 
