VAN NAME: SIMPLE ASCIDIANS. 
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loosely adherent coating but this is usually incomplete or thin and the 
surface more or less exposed. When cleaned the surface is roughened 
by small, scattered, granule-like papillae, and irregular rough processes, 
while in large specimens it is more or less rudely wrinkled. The large 
tubes arise from the upper part, a short distance apart, and are widely 
Text-fig. IS. — Caexirn retortiformis (Verrill). X 1.5. 
divergent and very unequal. The anal tube is much the longest, 
usually equaling in length the diameter of the body, very large and 
swollen at the base, curving outward and tapering to the end, which 
is blunt with a small square aperture, its surface is often roughened 
with irregular processes and in partial contraction is often sulcated. 
The branchial tube is usually about one-fourth as long, much smaller 
at the base, curved outward, the aperture surrounded with six, short, 
conical, acute, papillae or tentacular lobes, its surface below often 
rough with irregular verrucae. In contraction the tubes form large. 
low and rough verrucae, or may be wholly retracted and invaginated, 
together with a portion of the integument of the body around their 
bases. 
"When living the color is uniform light olive or grayish green. 
"The young have essentially the same characters as the adults, 
but are smoother" (Verrill, 1871a, p. 56). 
Hartmeyer (1903, p. 147) says of this species that it is the largest 
of the family known to him from the Arctic or Subarctic regions, and 
one of the largest Arctic ascidians. The largest specimen that he had 
seen was 75 mm. long and 60 mm. in height and came from Newfound- 
land; from the vicinity of Bear Island he also records specimens 
