MORSE: OBSERVATIONS ON LAMELLIBRANCHS 157 
it began to expand. The faintest jar of the table caused it 
slowly to contract. The edge of the mantle which is devoid of 
papillae projects slightly beyond the edge of the shell. The 
syphons which are separate, extend a little over half the length 
of the shell. The anal syphon, contrary to the usual condition, 
is more than twice the diameter of the branchial syphon; the 
end is rounded and surrounding the opening nine or ten long 
simple papillae project. There is no trace of a valve. The 
branchial syphon is shorter than the anal and supports only 
two papillae. The branchial tube when emerging, is inflated 
like a bladder as in Thracia. With the exception of CJlycymeris 
this is the only mollusk, so far as I know, in which the anal 
sj-^phon is larger in diameter than the branchial. Particles of 
flocculent matter adhere to the mantle anteriorly and even to 
the syphons and papillae. A wrinkled sheath extends beyond 
the posterior end of the shell embracing the base of the syphons. 
The foot is white, long, and attenuated and grooved above. The 
shell gapes at both ends. A rather fine membrane stretches from 
the edge of the shell nearly to the central line. Seen from above 
(Fig. 15, a) a long narrow opening runs back nearly to the beaks, 
the sides of the opening parallel. Seen from below (Fig. 15, b) 
the mantle is entirely open. Near the anterior end a round 
opening appears through which the foot projects; back of this 
an elongate, double-gourd-shaped opening is seen. This descrip- 
tion may be modified when ntiore specimens are studied fresh 
from the sea. A single specimen from which the drawings were 
made, was sent to me from Mount Desert waters to Salem by Dr. 
Harold S. Colton and it may have been in a moribund condition. 
The specimen was ovulating August 18. 
THRACIA CONRADI Couthouy. 
Fig. 16. Length, 87 mm. 
For years I have been accustomed to find the single valves 
of this species on Lynn Beach after storms. The shell is so 
brittle and delicate that the gulls in everj' case have broken the 
shell and devoured the soft parts within. Major John M. Gould 
collected a number of living Thracia from a big dredging machine 
in Portland Harbor and these I studied at his home. A live 
specimen was also sent me from Portland packed carefully in 
