AGARICUS ARVENSIS AND A. COTMULUS 
15 
or protoblem, is abundant, a distinct, though slight annulus may be 
formed at the base of the stem. This I have observed a few times in 
the case of Agaricus campestris. 
Smith figures diagrammatically the structure of Agaricus cam- 
pestris}^ Since there is no discussion of the morphological characters 
of Agaricus it is difficult to understand what his conception is of the 
universal veil and marginal veil in this genus. He figures a universal 
veil (U.V.) which extends from the base of the stem up over the entire 
carpophore and also a small ring at the base of the stem as the lower 
remnant of the universal veil after expansion of the plant. In addition 
to this an inner veil, the partial veil is illustrated as a distinct struc- 
ture which forms the annulus. In his diagnosis of Psalliota (1. c, p. 
170), he says: "Veil universal, concrete with the cuticle of the pileus 
and forming an annulus on the stem." The annulus which he figures 
from the universal veil is at the base of the stem while the structure 
marked annulus (A.N.) is midway on the stem. In his characteriza- 
tion of the family Agaricaceae (1. c, p. 11) he clearly distinguishes 
between the primary or universal veiV which forms the vol va and 
fragments on the pileus, and the partial veil. "In some species a 
secondary or partial veil is also present in the earlier stages spreading 
from the upper part of the stem to the edge of the pileus. This veil 
is finally ruptured and partly persists as a ring or annulus (A) encircling 
the stem." 
Cooke^^ says in his characterization of Psalliota {Agaricus), ''Veil 
universal, concrete with the cuticle of the pileus, and fixed to the stem, 
forming a ring." In his Tribe Psalliota Fries^^ says "veil annuliform, 
subpersistent, strictly speaking partial," and adds that a rudiment of 
a subuniversal veil is present in some species among which is Ag. 
campestris. This "subuniversal veil" is probably what I have here 
termed the primary "universal veil," or protoblem. It appears that 
some authors regard the partial veil in Agaricus and some other genera 
merely as a part of the "universal veil," while others regard it as a 
distinct structure. 
It does not seem worth while to inquire further into the literature, 
which is purely systematic, for the characterizations given are, in 
general, not based on studies of development from very young stages. 
Smith, W. G. Synopsis of the British Basidiomycetes, fig. 42. 1908. 
" Cooke, M. C. Handbook of British Fungi 1: 136, 137. 1871. 
^8 Fries, E. Syst. Myc. 1: 280. 1821. ''velum annuliforme, suhpersistens, 
proprie partiale.'^ 
