CERTAIN SPECIES OF Mucor 289 
placed by Lendner under the unbranched group. Hagem (1908) 
says that after a study of Wehmer’s species he believes that 
Mucor hiemalis has simple sporangiophores only in young cultures, 
later becoming profusely branched. M. Mucedo L., also, has always 
been classed as a simple form, yet in most descriptions branching is 
given as occurring rarely. It seems better, therefore, not to follow 
the traditional separation into branched and unbranched forms. 
The question of kind or type of branching is even more difficult 
to determine as both types often occur in the same species (M. 
saturninus). Moreover, different students of the group place 
the same species under different types of branching. Examples 
of this disagreement are shown in the case of M. sphaerosporus, 
M. griseo-cyanus, and M. silvaticus, all of which were described by 
Hagem. He placed the first two in the Racemo-Mucor group and 
the third in the Cymo-Mucor group. Lendner changes all three, 
placing the first two in the cymose, and the third in the racemose 
group. From this it is manifest that branching is a poor means 
of separation of species in a key. For these and other reasons to 
be given later, the writer has discarded this character in the 
preparation of the following key which contains the species studied 
from uniform, standard bread cultures. 
KEY TO SPECIES STUDIED 
oo Dyerbss cor, tallor over pie ee ae os ee 1. M. proliferus Schostak. 
eR BYE O18 —S Cin. tells gees aia eee ele weal) eer ote Eel to yyw) Era gael pov a eiace aR t ; 
7 birt tese:than ‘0-5 cms tallies. <4 ree pee Sa ra Sure na ewe Sie Be Ses 
, Spores globose, subglobose to suboval 2.2.6 ointment te eet ens 3 
b 
. Columella subglobose to pyriform...........- 4. M. abundans sp. nov. 
; Columelia globose to oval. oes ois oo a a oe ia hoe eee ve OR oe Fees 7 
Sporangia brownish; circinate sporangiophores 
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BEAL GHUGLTALUM sc 8c bi wos dea es pas ola mee 5 
. M. circinelloides Van Tiegh. 
Sporangia grayish; circinations not present..... 6. M. corticolus Hagem 
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Columelia spinescent; chlamydospores rarely in 
hi . plumbeus Bonorden. 
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isvuaniiaibnet: LE poe ET ee ee eed aye 8 . Sphaerosporus Hagem. 
