BRACHIOPODA. 
25 
development of its platforms and other interior characters, close upon Lingulops, 
the genus which presents the first deviation, in this direction, from Lingula. 
Externally, neither Lingulops nor Lingulasma may be distinguished from Lin¬ 
gula, but, notwithstanding this exterior linguloid aspect, both exhibit the most 
positive affiliations with the genus Trimerella. Lingulasma is represented by 
a single species, and by the favor of Mr. Charles Schuchert we have had at 
our disposal a number of specimens from the Hudson group at Wilmington and 
Savannah, Illinois, including the internal cast which has served Mr. Ulrich the 
purposes of generic diagnosis. These specimens preserve both external and in¬ 
ternal features, the cast referred to being in a most favorable condition for study. 
In strong contrast to the minuteness of Lingulops is the very considerable 
size of Lingulasma, and though this difference fails to affect the external linguloid 
character of the shell, it is to be regarded, in unison with other features, as evi¬ 
dence of progress in the assumption of the characters of the large, thick-shelled 
Trimerellids. The specimen figured on Plate II would be unusually large for 
a species of Lingula. 
Primarily, in reference to the determination of the valves of Lingulasma, we 
cannot hesitate to regard as the pedicle-valve that which bears the peculiar 
pedicle-sheath and faint anterior median septum. The brachial valve is 
then characterized by the strongly elevated septum. Such determination 
is in harmony with the characters of the respective valves in Trimerella and its 
closer allies, the stronger septum always appearing in the brachial valve, but it 
fails to agree, in this' respect, with Lingulops, where the septate valve bears 
accessory evidence of being the pedicle-valve. We are, however, inclined 
to regard this septum or low ridge in the pedicle-valve of Lingulops as a rem¬ 
nant of its inheritance from Lingula, rather than a newly assumed Trimerel- 
loid character. 
A very remarkable feature in Lingulasma is the enclosed pedicle-sheath. 
This takes the form of an arching triangular shelf extending from the 
apex for about one-eighth the length of the valve. Its surface features 
are precisely those seen in the cardinal area of Trimerella, viz., a broad 
