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PACIFIC SCIENCE, Voi, VIII, July, 1954 
ured are S. fustformis or S. maxima (see es- 
pecially Herdman, 1888; Apstein, lS9Ab; Rit- 
ter, 1905; Ihle, 1910), although these were all 
considered S, fustformis. I am inclined to re- 
gard the very large specimens described by 
some of these authors as S. maxima, but this 
is only speculation. 
There is less difficulty in distinguishing the 
two species in the aggregate generation than 
in the solitary generation. Body muscle ar- 
rangement is a poor means of distinction 
(Stiasny, 1926). Nevertheless, it has been the 
main basis for differentiating 5. fustformis from 
other species. In the POFI collections, some 
individuals of S. maxima were found in which 
M IV and V touch laterally (usually con- 
sidered a character of S. fusiformis), and many 
specimens of S. fusiformis were found in which, 
on either one or both sides, M IV and V do 
not touch. Other body structures, such as 
test, gut, position of embryo, and ciliated 
groove, are similar or intergrade between 
them. The differences in mouth musculature 
are the only certain means of distinguishing 
the two species in all specimens examined. 
In 5. maxima, ventral lip sphincter 4 (M bs) 
is continuous, whereas in V fusiformis it is 
interrupted; there are also other differences as 
shown in Figure 15. 
The great difference in size is usually a 
useful means of distinction between the spe- 
cies for both solitary and aggregate specimens. 
Genus Weelia gen. nov. 
The genus is characterized as follows: In 
both generations, transverse ribs of the gill 
bar meet dorsally, becoming reduced in width 
sharply toward the ventral surface so that they 
are far separated from one another ventrally 
(Fig. 16); gut in state E of Ihle and Ihle- 
Landenberg (1933) in both generations; ag- 
gregate form with five body muscles that form 
two groups dorsally (M I-III, IV-V); body 
muscles interrupted ventrally in both forms; 
no independent muscle in the posterior pro- 
jection of the aggregate form; solitary form 
with eight (rarely nine) body muscles of which 
M I-IV are either fused, joined by muscle 
strands, touch, or approach one another dors- 
ally; body muscles may be split into branches 
laterally, sometimes are fused laterally, thus 
tending to vary considerably; no attachment 
organs in the solitary form (excluding lips 
and cloacal siphon) ; test of the solitary form 
(in POFI specimens) bears a varying number 
of thickened white patches that are arranged 
in rows; or, according to Brooks (1893), Se- 
well (1926), and Stiasny (1926), there are 
seven longitudinal ridges on the test-two 
dorsal, two lateral, and three ventral, with a 
posterior ridge joining the midventral ridge. 
I regard Salpa cylindrica as sufficiently differ- 
ent from the other species of Salpa to be 
placed in a new genus, Weelia, named to 
honor Dr. P, B. van Weel of the University 
of Hawaii, who has contributed so signifi- 
cantly to the present study. The only known 
species, Weelia cylindrica, is the type. 
Weelia cylindrica (Cuvier) 1804 
Figs. I6c, \la-f 
Salpa cylindrica Cuvier, 1804: 381; Bomford, 
Fig. 16. Diagrams of a part of the gill bar of the 
solitary form, a, Salpa maxima; b, Salpa fusiformis; c, 
Weelia cylindrica. 1, ventral aspect; 2, lateral aspect. 
