110 ROYAL SOCIETY OF CANADA 
the writers hands, all resembling specimens being referable to 
Iphidea pannula. (See below.) 
The following species appear not to have been in Mr. Walcott’s 
collection, received from the Dr. Rominger. 
IPHIDEA PANNULA, White sp. 
Fine examples of this species were found in the Mt. Stephen 
collections. They show well the characteristic ornamentation, which 
resembles that of Obolus (Botsfordia) pulcher in that the cancellated 
ornamentation is developed chiefly on the middle zone of the shell, 
the front part being concentrically striated only. Still, there are 
dorsals which show the cancellation over nearly the whole surface. 
The shell has the convex pseudo-deltidium characteristic of Iphidea. 
No examples showing the interior of the valves were obtained. 
There are specimens of this shell in both the Walker and the 
Canadian Geological Survey collections. 
ACROTHELE SUBSIDUA, White. 
Mr. Walker’s collection contains several examples of the valves 
of this species, usually much flattened. One or two show well the 
concentric ridging and the more minute, somewhat wavy ridglets 
between. One dorsal is 9 x 10 mm. in size. Owing to the crushing, 
the internal features are obscure in these valves. 
Some good examples of this species were found in the collection 
received from Mr. Walker. 
OBozus ELA, Hall & W. 
Comparatively few examples of this species were found, and they 
do not show good interiors; still the discoid, circular form agrees better 
with Obolus than Lingulella; and the position of the central muscles, 
so fai as they can be made out, corresponds to Obolus. Perhaps the 
low broad cardinal area of the ventral valve accords more decidedly 
with Obolus than the other peculiarities of the valves, which are 
modified to suit the discoid form of the valves. 
The largest valve observed was a dorsal, somewhat abraded, 
9 x 103 mm. across. The species is somewhat “ satchel ”-shaped. 
Mr. Walcott in an MS. note remarks that this species varies greatly 
in different localities and sediments. He refers it to his new sub- 
genus Westonia on account of its surface which is not shown in the 
few specimens in my hands. 
