Pacific Salpidae — YouNT 
299 
continuous with thin test of cloacal siphon; 
dorsal posterior projections bearing a blunt, 
straight, posterior spine and a curved ventral 
hook; each projection also forming' a ven- 
trally directed posterior ridge that joins the 
same ridge of opposite side midventrally; at 
joint, ventral posterior projection formed; 
each dorsal posterior projection bearing lat- 
erally an anteriorly directed lateral ridge; ven- 
tral to this, formed at the posterior ridge, a 
ventrolateral ridge courses anteriorly; ven- 
trally a midventral ridge continuing anteriorly, 
dividing into two that continue to the chin; 
chin and mouth covered by thin test; inter- 
nally test with rather large gut cavity, no 
elaeoblast cavity; cavity for posterior ventral 
attachment organ not present in typical spec- 
imens (may be present in large asperate spec- 
imens); margin of gut cavity smooth. The 
asperate form of this species is similar to the 
typical form, except that its ridges are spiny 
and the test has more thin area, being thick 
only posteriorly, at the chin and upper lip. 
and along ridges (Fig. 11^). Muscles: Eight 
body muscles; M I-III and VIII-x usually 
fuse, touch, or converge but may be sep- 
arated; no attachment organ between M VI- 
VII. Ciliated groove: Usually forming shallow 
open bend (Fig. llh) but may form a large 
structure resembling that of Salpa maxima 
(Fig. 11^). Viscera: Gut compact, in condition 
E (Ihle and Ihle-Landenberg, 1933); endo- 
style straight; stolon usually coursing ante- 
riorly, turning abruptly and coursing around 
left side of gut, but may form a tight circle 
around gut. 
AGGREGATE FORM: More than 10 specimens 
examined with length range of 5-37 mm. 
(Fig. 12). Test: In typical form (Fig, 12^), keg- 
shaped, smooth; with one anterior and one 
posterior end projection; each may be as long 
as body; dorsal longitudinal depression ex- 
tending onto end projections, limited later- 
ally by dorsal limiting elevations; ventrally 
test gradually raised, forming a relatively small 
gut swelling. There is an asperate form (Fig. 
Fig. 12. Salpa fusiformis. aggregate form, a, Nonspiny form, dorsal aspect; b, asperate form, dorsal aspect; 
c, another asperate specimen, dorsal aspect; d, same specimen as b, dorsal aspect of ciliated groove and associated 
structures; e, ventral aspect of ciliated groove, from d. 
