Neck Extensions in Folliculinids — Matthews 
f — 1 
100 fj 
FIG. 2. Metafolliculina andrewsi showing: a, slight, 
distal fold of right peristomal lobe; b, indistinct, distal 
region of neck extension; c, left peristomal lobe curved 
in a semicircle at right angles to main, longitudinal 
axis of neck; d, distinct, proximal region of neck ex- 
tension; e, lip of neck; f, neck; and g, portion of body. 
c) were carried aloft, sometimes the right lobe 
( a ) but as frequently the left ( c ) formed a 
semicircle at right angles to the longitudinal 
axis of the neck (/) and, in this position, was 
finally carried above the lip (e). The other lobe, 
which was slightly folded near its distal end 
(a), appeared as if to tap or "feel” an indis- 
cernible neck boundary. Not once, even when 
both peristomal lobes were free, was any activity 
of the pectinellae detected. Relaxation and con- 
231 
traction of the body continued without inter- 
ruption throughout the day. Because a slight 
body secretion followed each contraction, it 
appeared that the peristomal lobes, functioning 
like a plasterer’s trowel, merely carried this 
material aloft and spread it rather than pro- 
duced it themselves. Gradually, the proximal 
portion of the extension ( d ) darkened some- 
what and became clearly discernible, but the 
distal portion (b) became only vaguely so. At 
4:00 PM the extension, still indistinct distally, 
measured approximately 66/x. The organism 
now lay in the proximal portion of the sac. 
After perhaps 2 hours of "inactivity,” this 
sessile stage metamorphosed into a motile swim- 
mer which, following three or four unsuccessful 
attempts, finally swam free of the original lorica 
leaving, as usual, the distinct green area in the 
proximal region of the sac which marked the 
old body attachment point. Unlike other ob- 
served swimmers, this one "crawled” slowly 
along the surface of the submerged glass plate. 
Its vermiform body, only slightly attenuated 
posteriorly, measured 415 g long but only 33g 
wide. The following morning this swimmer was 
found dead not far from the lorica whose neck 
had been extended. As far as was discernible, it 
had made no attempt to secrete a new lorica. 
The extension (Fig. 3) had darkened through- 
out its entire length but unfortunately was 
frayed distally (a) and devoid of lip (a) and 
spiral whorls ( b ) . 
Were this the only case in point, one might 
accept for all neck extensions Andrews’ (1923: 
242) statement: 
While the original [lorica] is made by an 
animal without lobes which then transforms 
into the lobed form, it seems probable that 
the extensions are added by the animal when 
with quite different anatomy at the anterior 
end. ... If true that the perfect form can 
secrete spiral tube and terminal lip without 
the usual special neck and mushroom shape 
it would seem to follow that it is not so 
much one specialized part of the body that 
makes the form of the dwelling as it is 
temporary contractions and secretions that 
may be active in very different parts of the 
body, since the area of secretion that must 
have been active in the secondary tube and 
