270 
PACIFIC SCIENCE, Vol. XI, July, 1957 
TABLE 1 
Summary of Setation of Second Segment of Legs Found in Twelve Specimens of Teredicola typica 
(sp = spine; s = seta; number in parentheses represents that of opposite ramus; in two females the segment 
was previously broken off on one side, as indicated by blank space.) 
LEG 1 
LEG 2 
Exopod 2 
Endopod 2 
Exopod 2 
Endopod 2 
9 
4(4)sp 
4(4)s 
l(Dsp 
5(4)s 
3(3)sp 
5(5)s 
2(2)sp 
4(3)s 
4(4) 
5(4) 
KD 
6(5) 
3(3) 
5(4) 
2(2) 
4(5) 
4(4) 
5(6) 
KD 
6(5) 
3( ) 
5( ) 
2(2) 
5(5) 
4( ) 
5( ) 
Kl) 
5(5) 
3(3) 
5(4) 
2(2) 
5(5) 
4(4) 
2(3) 
KD 
4(5) 
3(3) 
4(4) 
2(2) 
4(5) 
4(3) 
3(5) 
KD 
5(5) 
3(3) 
3(4) 
2(1) 
4(5) 
4(4) 
5(5) 
KD 
6(6) 
3(3) 
4(5) 
2(2) 
5(5) 
c? 
4(4) 
5(5) 
KD 
5(6) 
3(3) 
6(5) 
2(2) 
4(5) 
4(4) 
5(5) 
KD 
6(6) 
3(3) 
6(6) 
2(2) 
5(5) 
4(4) 
5(5) 
KD 
6(6) 
3(3) 
5(5) 
2(2) 
5(5) 
4(4) 
4(6) 
KD 
6(7) 
3(3) 
5(5) 
2(2) 
5(5) 
4(4) 
5(5) 
KD 
6(7) 
3(3) 
4(5) 
2(2) 
5(5) 
species. The differences between the two de- 
scriptions are not due to variation, but to 
omissions or misinterpretations in the original 
description. Most of these can be easily re- 
conciled with or explained by comparison of 
the statements and illustrations in Wilson’s 
description, or with the specimens used in 
this study. 
Teredicola typica clearly shows in both sexes 
the same recognizable number of body seg- 
ments most commonly found in both free- 
living and parasitic cyclopoid copepods — 
that is, nine segments in the female and ten 
in the male. As is shown both by Wilson’s 
illustration and those given here, the tumid 
condition of the anterior part of the female’s 
body does not obliterate the number of seg- 
ments included in the metasome in either 
dorsal or ventral view. The lateral expansions 
are constricted between the segments whether 
the specimen is newly molted or older, ex- 
panded or contracted. The somite of leg 1 is 
thoroughly united with the cephalic segment 
as indicated in ventral view (Fig. 2), and the 
three succeeding expansions are obviously in- 
terpretable as the somites of legs 2-4, or 
thoracic segments 2-4. The fourth thoracic 
segment cannot be the first reduced segment 
as given in the original generic diagnosis. 
Whether any real suture lines are ever present 
between the expanded segments is difficult 
to decide with certainty from preserved ma- 
terial. In well expanded specimens, an inter- 
segmental membrane was prominent (Fig. 2), 
and no definable lines of separation were no- 
ticed. In less expanded specimens, complete 
or incomplete lines were observed, of which 
some at least were 'Told” lines of the mem- 
brane. Thus, although highly modified, the 
metasome of Teredicola typica does conform 
in the female to the "standard” segmentation 
of other cyclopoids and exhibits external evi- 
dence of this. 
There are five reduced posterior segments 
(urosome) in the female, rather than six as 
shown by Wilson. It follows from the division 
of the metasome that the first of these is the 
somite of the absent fifth leg (fifth thoracic 
segment). The second reduced segment is the 
genital segment, as is clear from the attach- 
ment of the ovisacs, which are shown by 
Wilson attached to an additional segment 
posterior to the second segment, an error 
corrected in an illustration by Edmondson 
(1945). The extra segment of the urosome 
shown in this position by both Wilson and 
