44 THE NAUTILUS. 
granum ; but besides certain differences in form, this has an Amni- 
coloid operculum, while in granum it is Valvatoid. 
The specimens from River Rouge are smaller and more elongated 
than average shells of the type lot; those from Reed’s Lake are 
fairly typical in form, but perhaps a little thinner. 
The name is in honor of Mr. Bryant Walker, to whose acumen 
the discovery of the form, and of its distinctness from known Michi- 
gan Amnicolide, is due. 
While investigating the characters of the above species, I have 
had an opportunity, through the courtesy of Prof. W. H. Dall, to 
examine the types of Amnicola parva and A. orbiculata Lea, de- 
scribed from Springfield, Ohio. 
A. parva is like A. limosa in the umbilicus and obtuse apex, but 
is smaller with the whorls particularly tumid just below the suture, 
producing a somewhat shouldered appearance, such as characterizes 
Amnicola cincinnatiensis (Anth.). The same form occurs at Joliet, 
lilinois, Muscatine, Iowa, ete. It measures alt. 3°8, diam. 3°2 mm. 
or somewhat smaller. Whether it is a stunted form of limosa due 
to unfavorable station, or is constantly distinguishable I have not 
ascertained ; but it is at all events quite recognizable. The types 
show more or less blackish incrustation about the spire, and evidently 
did not occur with Lea’s specimens of orbiculata. 
A. orbieulata is absolutely identical with A. limosa var. porata 
Say. The specimens vary between the widely umbilicated porata 
form, and an intermediate form. They are finely grown shells, quite 
fresh though without opercula, and rather corneous than “ yellow- 
ish” as Lea says. There was no “* mistake” about Lea’s “specimen 
of this species among many small shells which were thrown together 
in a box, as being collected from our vicinity” (Philadelphia), for 
fimosa and porata are abundant in both the Delaware and Schuyl|kill 
rivers. ‘Two of Lea’s type lot measure : 
Alt. 5, diam. 4 mm. 
Alt. 4, diam. 4 mm. 
A NEW SPECIES OF TEREBRA FROM TEXAS. 
BY W. H.-DALL. 
Some years ago the Hon. J. D. Mitchell, of Victoria, Texas, sent 
to the National Museum a much dilapidated specimen of Terebra 
