MORSE: OBSERVATIONS ON LAMELLIBRANCHS. 
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ually; some have a pale purplish tint, others are light brown, 
and one individual was dark gray mottled with black spots. 
The branchial syphon is somewhat broader than the anal syphon; 
its opening is fringed with seventeen short, rounded papillae 
of nearly equal size; below this is another circle of similar papillae. 
The anal syphon has a short valve with the opening surrounded 
by a circle of short, round papillae of equal size. At the junction 
of the two openings there is a break in the papillae. The syphons 
are Ught brown, strongly mottled with black dots; the papillae 
as well are maculated. (Fig. 17, a, single papilla enlarged.) The 
base of the syphons is surrounded by a thick collar of coarsely 
wrinkled tissue, nearly transparent. This issues from the shell 
as the syphons protrude. When Pandora is placed on its side 
the short syphons turn abruptly upward at right angles to the 
longitudinal axis. I have never seen a young Pandora and 
therefore know nothing about the protoconch. 
LYONSIA HYALINA (Conrad). 
Fig. 18. Length, 19 mm. 
The shell is very thin and delicate, somewhat nacreous within. 
It is marked with rows of radiating lines from the beaks which, 
under a moderate power, are seen to be defined by minute 
Fig. l.S. — Lyomia hyaline (Conrad). 
refractive nodules which entangle particles of sand. Between 
these lines are five or six microscopic lines as shown in Fig. 18, a. 
The edge of the shell is sharp with a shght thickening and round- 
ing on the anterior portion. The ossiculum is rounded anteriorly 
and square posteriorly with its edge slightly incurved (Fig. 18, b). 
A deHcate membrane stretches across the posterior dorsal margin 
