A NEW GENUS AND SEVERAL NEW SPECIES OF LAND- 
Sheer Come CrED IN CENTRAL MEXICO BY 
DOCTOR EDWARD PALMER 
By WILLIAM HEALEY DALE 
Doctor Edward Palmer of the U. S. Department of Agriculture 
has for a good many years been engaged in Mexico, where his 
travels have been extensive, collecting plants for the National and 
other herbaria. In the course of his researches he has from time to 
time collected landshells, which have been added to the National col- 
lection. Ina recent expedition to the State of San Luis Potosi, at a 
height of 7,200 feet above the sea, on the range locally known as 
the Alvarez Mountains, he obtained a small collection which proved 
to contain a very remarkable new genus allied to Holospira, and 
several new species of known genera, which form the subject of 
this paper. 
Family UROCOPTID/= 
HENDERSONIA’ new genus 
Shell discoid, with a single internal parietal lamina, the aperture 
and part of the last whorl free from the disk and recurved so that 
the holostomatous aperture lies above the disk and with the plane 
of its margin nearly or quite parallel with the plane of the shell-coil. 
Soft parts resembling those of Holospira. 
This genus is dedicated to Mr. John B. Henderson, Jr., known 
in connection with his studies of the Antillean landshells. It is 
an animal of the Urocoptid group which has taken upon itself a 
discoid form, something hitherto unknown in that assembly and 
therefore of unusual interest. 
HENDERSONIA PALMERI n. sp. 
(Piate XLIII, Fricures 1-4) 
Shell thin, depressed, nearly flat above, with the periphery com- 
pressed and keeled; the umbilicus wide, shallow, saucerlike, its 
margin subangular; the suture distinct, rather deep, not channelled 
but with the whorls between distinctly rounded; nuclear whorl pol- 
ished, rather prominent, the eight subsequent whorls subequal, 
closely coiled; the termination of the last whorl divergent, wholly 
*See note at page 2390, postea. 
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