th-e South Austndlan Naturalist. 
/ 4 - 
NOTES ON DREDGING TRIP, FEB., 20th, 1926. 
By F. Trigg. 
Weather conditions were perfect for this excursion — the 
exceptionally sanooth sea prevailing enabled operations to be 
conducted with comfort. The dredges were lowered in 5 fathoms 
of water about 6 miles from shore, almost opposite the mouth 
of the Port Adelaide River. 
The spoils recovered were, as usual, varied in character, 
enabling all to secure a good supply of those forms in which 
they were particularly interested. 
An outstanding incident was the passing of the dredge over 
a bed of the bivalve Lima angulata. These toothless-hinged white 
shells were in countless numbers of all sizes. The Lima weave, 
with their byssal threads, nests composed of marine fibre and 
shell fragments, allowing space only for vertical movement. 
Several juveniles may inhabit the same nest, but adult forms 
settle down to solitary, sedentary existence, each in their own 
compartment. When placed in a specimen jar, the full beauty of 
the shell is revealed. Moving swiftly through the wmter, sheals 
of gaily-colored mantle tentacles trail behind, which have con- 
siderable adhesive power. The shell itself has a rough, file-like, 
surface. 
Specimens of Cardhim pulchellum and C, racketti were 
noticed. The valves of the former, a small shell, are marked with 
groups of closely-laid pink rays, extending to the ventral edge. 
Several valves of Myodora and Clausinella tiara were collected. 
Myodora is peculiar in having one perfectly flat valve and one 
convex. Clausinella tiara is one of the smaller frilled bivalves 
very shapely when in good order, Both shells are coitiparatively 
rare. 
'Fhe univalves included the rare and interesting lyphis 
YatesiL Belonging to the great family of Muricidae^ its tubular 
spines, rounded aperture, closed-over canal, and long upturned 
siphonal tube, make it a most remarkable specimen. Tw^o ex- 
amples of Dentalium or tooth shell were collected, one, a young 
s,pecimen w^ell curved, and the other, an adult much less so. Nine 
and ten ribs were counted on these shells. Sigapatella calyptrae- 
formis w^as plentiful. This flattened univalve, though covered 
with a rough, brown, periostracum, was not difficult to discover, 
adhering to any flat surface among the general debris. Many 
other small shells were collected, and it was noticed that no 
specimen was too small to accommodate a still smaller hermit crab. 
