1 DISTRIBUTION 
COLOUR—HABITS 7 
depth of about eight inches. The greater part of the body is 
coiled in an even, cork-screw-like spiral, while the anterior end, 
including the front part of the branchial region, is maintained 
in a vertical position. The posterior end is also kept upright, 
and can be moved up and down in a vertical shaft opening on 
the surface, thus enabling the animal to eject the undigested 
sand from its anus. 
The coloration of Balanoglossus is often brilliant. That of 
D. kowalevskit* is as follows :—The “ proboscis” (cf. Fig. 1, B, p) 
is yellowish white; the “collar” (c) is brilliant red-orange 
(especially in males), with a white ring posteriorly ; the “ trunk ” 
(¢), the subdivision of which into “ branchial,” “ genital,” “ hepatic,” 
“abdominal,” and “caudal” regions is better indicated in other 
species (Fig. 1, A, b, g, h, ab), is orange-yellow, shading to green- 
yellow in the semi-transparent caudal region. The genital region 
is grey in females and yellow in males, a sexual difference in 
colour being common in Enteropneusta. The hepatic papillae of 
other species may be bright green. 
The odour of D. howalevshii resembles that of “ chloride of line 
with a faecal admixture,” while that of Balanoglossus aurantiacus 
suggests 1odoform. All Enteropneusta are said to have a more 
or less offensive smell. A species of Balanoglossus is known to 
be intensely phosphorescent.” 
The mouth (Fig. 7, m) is situated on the ventral side, at the 
base of the proboscis, and is concealed by the free anterior edge of 
the collar, which encircles the thin “ proboscis-stalk ” (Fig. 3, p.s). 
The animal has the singular peculiarity of being unable to close 
its mouth;* and thus, as it burrows through the ground, the 
sand which passes into the alimentary canal leaves it in a 
continuous column through the terminal anus.* The large coiled 
“castings” formed in this way between tide-marks enable the 
experienced collector to infer the presence of Balanoglossus ; and 
in a West Indian species described by Willey’ they are so large 
as to form “an important feature in the landscape at low tide.” 
The principal agents in burrowing are the proboscis and collar. 
An animal observed by Spengel pushed the tip of its proboscis 
into the sand, waves of muscular contraction meanwhile passing 
1 Quart. J. Micr. Sci. xxv. Suppl. 1885, p. 91. 
2 Pouchet, C. R. Ac. Sct. cii. 1886, p. 272. 
3 Kowalevsky, Mém. Ac. St. Petersb. (7) x. No. 3, 1866, p. 7. 
4 Spengel, Monogr. p. 474. 5 Zool. Res. Pt. iii. 1899, p. 256. 
