Tun Shells— Tinker 
303 
mentioned is one in which no well-defined reef 
exists. It is, moreover, the point on the island 
of Oahu which is nearest to deep water, the 
remaining parts of the island shore line being 
separated from deeper waters by an insular shelf 
some miles in width. 
Distribution: The distribution of the species 
in the Hawaiian Islands is not well known, but 
it can be said with some degree of assurance 
that the species previously known from this 
area are distributed from Hawaii northwestward 
to Ocean or Kure Islands, inasmuch as speci- 
mens are on record from several points along 
this chain. The range of the two species here 
newly recorded is unknown and their present 
scarcity will make their true distribution in the 
Hawaiian Islands unknown for many years. 
Family DOLIIDAE 
Shells large, ovate, thin, hard, with large ven- 
tricose body whorls, spirally ribbed, without 
longitudinal sculpture; aperture very large; spire 
short and small; umbilicated; anterior canal 
present, but short; outer lip simple; operculum 
absent in adult, thin and corneous in young; 
length, 2 to 9 inches. 
The mollusks which inhabit these shells are 
fascinating to watch for they are large and mus- 
cular creatures and active in their habits. The 
foot is large and fleshy and when expanded is 
more than twice the diameter of the aperture. 
The head bears a pair of elongated tentacles 
which are expanded basally and have eyes near 
their proximal end. The head bears in addition 
a long, large, cylindrical, tube-like proboscis 
which is extensible and very flexible and which 
ends in a kind of rosette. When undisturbed 
the mollusk glides rapidly along. The pro- 
boscis is held in a forward, slightly raised posi- 
tion forming a gentle S-shaped curve with the 
free end directed downward, and is waved 
slowly from side to side. 
Key to the Genera and Species of Hawaiian 
Doliidae 
1. Shells light in weight, thin, hard; outer 
lip simple; body whorl large; aper- 
ture very wide (Genus Tonna ) 2 
Shells heavier; outer lip strongly den- 
tate; body whorl less expanded; aper- 
ture considerably reduced, approxi- 
mately four times as long as wide 
Malea pomum Linnaeus. 
2(1). Outer surface of shell marked by a reg- 
ular recurring color pattern 3 
Outer surface of shell variously pig- 
mented without a regular recurring 
color pattern, blotched and streaked 
with various shades of black, brown, 
and yellow 4 
3 (2). Outer lip of shell crenate; outer sur- 
face of shell white in color, marked 
upon the ridges by quadrate brown 
spots; spiral ridges well developed, 
approximately as wide as the inter- 
spaces Tonna dolium Linnaeus. 
Outer lip without crenations; outer sur- 
face of shell brownish in color, 
usually covered by a network of 
white lines consisting of regular nar- 
row spiral lines which follow the 
grooves and which are connected by 
short, irregular, longitudinal lines 
crossing the ribs; spiral ribs present, 
but poorly developed 
Tonna perdix Linnaeus. 
4(2). Inner and outer lip of aperture marked 
with black; spiral grooves on outer 
surface of shell marked with black; 
ribs on outer surface of shell arched 
Tonna melano stoma Jay. 
Inner and outer lip of aperture not 
marked with black; spiral grooves on 
surface not marked with darker lines; 
ribs on outer surface of shell nearly 
flat Tonna canaliculata Linnaeus. 
Genus Tonna Bruennich 
Shells large, ovate, thin, hard, with greatly 
inflated body whorls; surface of shell spirally 
furrowed and ribbed, without longitudinal 
sculpture; spire low; aperture large; outer lip 
simple, with or without crenations; columellar 
lip broadly expanded; umbilicated, open or 
closed; operculum absent in adult, present in 
young. 
This genus includes about 2 1 species of which 
approximately one-third are fossils. Four spe- 
cies are known from the Hawaiian Islands. 
