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eye; latter just in front of M I, prominent. 
Viscera: Gut forming posterior loop at base 
of posterior projections beyond body margin; 
anus opening at esophageal level; testis oc- 
cupying left posterior projection; a caecum 
from the gut plus a smaller "problematic” 
organ, considered by Metcalf to be probably 
homologous with the same organ ( = blood- 
forming organ) of Ritteriella, occupying the 
right posterior projection; embryo located at 
region of posterior muscle mass on right side. 
Genus Helicosalpa Todaro, 1902 
I have not seen the report of Todaro (1902) 
establishing this genus. Ihle (1935) stated in 
regard to Todaro’s report, "Dutch die starke 
Enantiomorphie, dutch das Eehlen einer ring- 
formigen Anordnung der Blastozooide in der 
Kette und dutch die eigentiimlichen Haft- 
Flachen weicht Cyclosalpa virgula^ (Vogt) so 
bedeutend von den anderen Arten ab, dass 
Todaro (1902) diese Art zur selbstandigen 
Gattung Helicoslapa rechnete.” Ihle did not 
follow this classification, considering the spe- 
cies C. virgula to agree so closely with the 
other cyclosalpas in muscle arrangement and 
structure of gut that he thought it should not 
be separated from them. 
After careful examination of the species H. 
virgula and H. komaii, however, I am of the 
opinion that they are quite different from the 
species of Cyclosalpa; thus I agree with Todaro 
(1902). As Helicosalpa virgula was at that time 
the only known species of the genus, it must 
be considered the type. 
The genus may now be characterized as 
follows. 
1. There are two distinct gregarious forms 
produced on the stolon, the dextral and the 
sinistral individuals. Whorls are not produced 
on the stolon. Mirror imagery is shown in the 
arrangement of attachment organs, muscula- 
ture, tentacle over the ciliated groove, the 
ciliated groove, testis, and posterior projec- 
tion {H. virgula), eye, mouth, and cloacal 
siphon. Other variations in the two forms. 
although not mirror imagery, are the position 
of the testis and posterior projection (H. 
komaii), embryo, gut, and anus ("primary 
asymmetry” ofKomai, 1932; the mirror imag- 
ery is called "secondary asymmetry” by him). 
In a few other species of Salpidae (for ex- 
ample, Brooksia rostrata and Ihlea punctata) 
asymmetry occurs, but this apparently is sec- 
ondary asymmetry. 
2. There is no peduncle, only a blunt at- 
tachment organ by which the gregarious 
forms attach to the stolon. The body muscles 
do not enter this process as do the peduncle 
muscles of Cyclosalpa, 
3. The solitary form possesses dorsal and 
ventral longitudinal muscles which are con- 
tinuous with M I; the dorsal longitudinal 
muscles are paired {H. virgula) or united (H. 
komaii). The ventral longitudinal muscles are 
always paired; they are distinct from most 
transverse muscles {H, virgula) or joined by 
all transverse (body) muscles (if. komaii). 
4. The anus of the solitary form is turned 
widely posteriorly from the anterodorsal re- 
gion of the gill bar, forming a rectum. 
The nearest known relative of Helicosalpa 
virgula and H. komaii is probably Cyclosalpa 
bakeri. Metcalf (1918) included H. virgula and 
C. bakeri in his group Cyclosalpae asymmetricales 
but did not attain a phylogenetically accurate 
division, stating: "The division of the sub- 
genus into Cyclosalpae symmetricales and Cyclo- 
salpae asymmetricales , while truly descriptive 
of the existing conditions, does not represent 
accurately degrees of relationship, for Cyclo- 
salpa bakeri, an asymmetrical form, finds it 
nearest relative in C. floridana, an aberrant 
member of the group symmetricales." 
The separation of H. virgula and H. komaii 
into a separate genus is considered phylo- 
genetically valid, distinguishing them from 
the cyclosalpas. 
Helicosalpa virgula (Vogt) 1854 
Fig. la-d 
Salpa virgula Vogt, 1854: 11. 
