1910.] NATURAL SCIENCES OF PHILADELPHIA. 125 
Three lamelle: axial, superior and basal— 
Length 10, diam. 3.4 mm. 
(Shells with strong ribs throughout.) 
One lamella: axial— 
Length 12, diam. 3.3mm. (Type specimen, pl. XIII, fig. 3). 
Smet Obi = Foy Biot ce 
c i oc 3.4 ¢ 
“cc 1 ee “cc 3.4 79 
79 i “cc 3.4 (73 
Beale is aR) 
Sema OlaGes 08! BS a 
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eee. 6) Bki24 1 
eat ny Beart) 6% Ba |e 
OOM VO Ae CB ay | 
ELS (ee SIM ee eG 
(73 10.3, a3 3 (<9 
6c 10, (79 3.3 ce 
ee A) sk 2 Bi Oy 
(79 10, “ce ayy (73 
(73 IOP (73 3:3 (a4 
CUNEO RN 
Two lamell: axial and superior— 
Length 11.7, diam. 3.4 mm. 
(79 tt. “cc 3 i 4 “e 
PRO Gar we Bo! Day 
6“ 10, 6b 8.5. || \ 6 
i 9, sa ice) ‘“‘ Specimen figured, pl. XIII, fig. 5. 
Station 2.—Similar specimens occurred at higher levels at Station 2. 
A large proportion of these specimens are ribbed throughout. The 
lamelle in 15 shells opened are as follows: 
10 shells have 1 lamella, the axial. 
5 shells have 2 lamelle, axial and superior. 
Station 3.—Shells were taken under stones on the sunny side of the 
ridge, and another lot on the summit of the ridge. The majority of 
the shells are ribbed throughout, but some have the penultimate 
whorl nearly smooth. Most specimens are 10 to 11 mm. long. In 
13 opened: 
