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PACIFIC SCIENCE, Vol. VIII, July, 1954 
pressions; with one lateral attachment organ 
on each side over cloacal muscle x. Muscles: 
Ten large muscles of which the first is M C; 
M I fused with C dorsally; M VI-VII fused 
ventrally; remaining body muscles distinct 
dorsally and ventrally; M C, I-VII, and x 
forming complete rings; M VIII interrupted 
ventrally, continuous dorsally; ventral oral 
retractor extending posteriorly on each side, 
branching into two longitudinal bands, a 
dorsal one extending to posterior edge of M 
VII and a ventral one extending to space 
between M III and IV (touching IV in em- 
bryo); longitudinal muscles coursing inter- 
nally to body muscles; cloacal retractor ex- 
tending anteriorly beneath x to M VIIL 
Ciliated groove^ ganglion and eye: Ciliated groove 
simple, anterior to M C. Ganglion and eye 
just beneath M C. Viscera: Gut compact, in 
condition D (Ihle and Ihle-Landenberg, 1933) ; 
stolon, according to earlier investigators, 
forming a tight spiral limited to ventral region 
of gut (no stolon present in POFI specimens). 
AGGREGATE FORM: Mote than 10 specimens 
examined with length range of 18-23 mm. 
(Pig. 10b,c). Test: Not observed but body 
flabby, thus test probably without permanent 
elevations or depressions. Muscles: Asym- 
metric; six body muscles present; M I-II 
join dorsally as do III-IV and V-VI; all 
muscles interrupted ventrally; M C broad; 
M VI on one side extending in broad band 
around ventral surface of gut; M II on side 
opposite latter portion of VI extending pos- 
teriorly on ventral surface toward opposite 
side to between M V and VI. Ciliated groove, 
ganglion and eye: All anterior to M I; ciliated 
groove straight, simple; ganglion and eye 
posterodorsal to it; eye projecting dorsally 
toward a small opening in mantle above it. 
Viscera: Gut compact, in condition F (Ihle 
and Ihle-Landenberg, 1933); embryo located 
on right side just under M V. 
On examination of the literature of Ihlea 
punctata and 1 . asymmetrica, a large number of 
contradictions, seemingly incorrect observa- 
tions, and similarities in the descriptions of 
the two so-called species are noticeable. 
Therefore, if some of the earlier works 
which seem to be permeated with faulty ob- 
servations are disregarded, the reported dif- 
ferences between the species and my criticisms 
of them may be summarized as follows: 
1. In Ihlea asymmetrica aggregate there are 
no pigment cells ventrally on the test, whereas 
in /. punctata these are present. The presence 
or absence of pigment is probably largely 
determined by length of exposure to the pres- 
ervation fluid. 
2. In /. asymmetrica agg. all body muscles 
are interrupted ventrally (Ihle, 1912; Tokioka, 
1937) or only M VI is a ring (Metcalf, 1918), 
whereas in L punctata all muscles are inter- 
rupted ventrally (Streiff, 1908; Ihle, 1912; 
Metcalf, 1918). Metcalf (1918) performed his 
study on stolonic individuals of 1 . asymmetrica 
which perhaps had not completed their 
growth and thus possessed a ring muscle; 
or he made an error in his observation. 
3. In /. asymmetrica agg., M I-II and V-VI 
join dorsally to form groups, M III and IV 
remain separate (Metcalf, 1918), or M I-II, 
III-IV, and V-VI form groups, the second 
group (III-IV) joining the first (Ihle, 1912; 
Tokioka, 1937). On the other hand, 1. punc- 
tata forms two groups — M I-II and V-VI — 
and M III-IV remain separate (Streiff, 1908; 
Metcalf, 1918), or M I-II and V-VI form 
groups, M II-III remain separate but ap- 
proach Mil (Traustedt, 1893; Apstein, 1906^). 
These differences in muscle grouping seem 
to be only individual variation. They overlap 
in part and are considered nonuseful here. 
4. In Ihlea asymmetrica sol., the dorsal long- 
itudinal muscle extends to M VIII; the ven- 
tral longitudinal muscle extends to beneath 
M V (Ihle, 1912; Metcalf, 1918). In 1. punc- 
tata, on the other hand, the dorsal longitu- 
dinal muscle extends to between M VII and 
VIII (Apstein, 1906^/; Streiff, 1908; Ihle, 
1912; Metcalf, 1918); the ventral longitudinal 
muscle extends to between M III-IV (Ap- 
stein, 1906^; Streiff, I9O8; Ihle, 1912; Met- 
calf, I9I8). There is obviously no difference 
