204 
THIRTEENTH REPORT. 
THE OCCURRENCE OF ZYGORHYNCHUS MOELLERI IN MICHI- 
GAN. 
H. GROSSMAN. 
In the year 1SSG P. Yuillemin described a new' species of Mucor to 
which lie gave tlie name of Mucor heterogamus. He called it heterog- 
amus because unlike most of the Mucor species, the zygospore is formed 
P'/ate X 
5 
ZYGORHYNCHUS MOELLERI. DEVELOPMENT OF ZYGOSPORES. 
by the union of two so-called copulating branches, which are unlike 
both in shape and size. These copulating branches are formed in the 
following manner: At the end of the main branch, or in some cases, of 
the side branches of the fungus mycelium a cross wall was formed; that 
portion of the end which is cut off, however, continuing to grow in length 
but remaining thin and slender. Just in back of the cross wall, a side 
