LICHENS AND LICHEN. PARASITES

DODGE-LIOHENS AND LICHEN PARASITES 143
carbonaceous parathecium, asci 8-spored; ascosFores with three transverse septa and one or two
longitudinal or oblique septa, producing a few-celled muriform spore similar to those of Co!lema
~ect. Blenothdlia which finally becomes slightly yellowish brown. Were it not for the extreme form
of S. megalospora only the darlrer parathecium and the muriform spore distinguish A. cymosa from
Stereocaulon where the sterile material was referred. Until more information is available, it is
largely a matter of individual opinion whether the generic limits should be circumscribed to
include only S. megnIospra or enlarged to include S. cymosum. Although Th. Fries described this
genus in the Usneaceae, neither species seems related to Oropogon Th. Fries, the only genus of
Usneaceae with muriform spores.
ARWPSIS MECJALOSPORA Th. Fr.
Argopsis megalospora Th. Fr., Nova Acta R. Soc. Upsal. III,2,325 ; 1858.
Sterenocaulon Argus Hook. f. & Tayl., London Jour. Bot., 3,653 ; 1844 : Cryptog. Antarct., 84 ; 1845 :
F1. Antarct., 1, 196; 1845 pro parte.
Type: Campbell Island, on rocks on mountains, J. D. Hooker (Voy. "Erebus & Terror") in
Upsala, a duplicate in Taylor Herb. at Farlow Herb. at Harvard Univ. The sheet marlred
Stereocadon Argus Tayl. contains four plants glued to the sheet. When they were studied by
Miiller-Argau in 1887, he lettered the plants "a"and "b" and annotated the sheet: "a. ArgopsG
ntegalospora Th. Fr. ; b. Stereocaulon ramdosum v. mucrocarpum Bab. Nyl." Ddplicates of the
latter plants were taken as the type of 8. Argus when Fries segregated A. megalospora in 1858.
The following formal description is based on,the two individuals marked "a" by Miiller-Argau.
The confusion is not surprising as the specimens resemble each other closely in microscopic char-
acters, having the same type of branching and phyllocladia. The primary branches of Argup-
sis megalospora are somewhat flattened, the cephalodia are much less conspicuous and darker in
colour, the exciple is verrucose and the disc tends to remain flatter-all characters which would
have been considered in Taylor's time.
Three courses of nomenclature are open. One may follow Fries and Miiller-Argau, retaining
8. Argw for the plants not Argqpsis in spite of the fact that the characters of the description and
most of the figures on the plate are clearly those of Argopsis; or one may accept the specific epithet
Argw in Argopsis, reducing A. megdospora to synonymy with it and call the Stereocaulon plants
5. Argodes Nyl. or refer them elsewhere in Stereocaulon. Finally one may reject 8. Argus as a
mmen cmfusum (International Rules, Art. 64). In the following treatment I have preferred to
follow Th. Fries.
Thallus 4-5 cm. tall, branching near the base, closely dichotomous appearing sympodial, base
2.5 mm. in diameter, somewhat flattened and obscurely striate sulcate longitudinally; decorticate,
smooth, secondary branches more terete, verrucose, the verrucae passing into short terete obtuse
phyllocladia, cortex dull and peeling off, leaving a slightly tomentose surface; cephalodia not
abundant, small, cerebriform, of the 8. ramdosum type. Podetial cortex 110-130p thick, formed
of a palisade of large thick-walled hyphae about 15p in diameter, protoplasts about 7. 5p, the outer
15p more or less decomposed, often peeling off; algal layer about 55p thick, more or less interrupted,
extending to the base of the parathecium, composed of more or less spherical colonies about 15-20p
in diameter loosely imbedded in lobsely woven, slender medullary hyphae, algal cells spherical
4p in diameter, protococcoid ; chondroid axis of densely woven rather thick-walled hyphae 4p in
diameter extending in a thin layer under the parathecium and merging with it,.