134 THE AUSTRALIAN NATURALIST. 
are prominent. It has, however, been pushed out of shape a 
little by the rock pressure. 
The three other fossils, were of the upper marine series; two, 
collected by me at Wollongong (Cleobis grandis and Maeonia 
audaxz), and a good specimen of Martiniopsis subradiata from 
Gerringong. This latter was collected two years ago, and 
shows the internal structure of the tractiopod remarkably well. 
ROOT FASCIATION IN CYCADS. 
By A. A. Hammon. 
In a note in this journal (V. 4, p. 28), attention was drawn 
to the occurrence of apogeotropie roots in Cycadaceae, with 
special reference to the coral-like formation of the aerial roots 
of Encephalartos villosus. In a recent work dealing with mal- 
formations, abnormalities, &¢., Worsdell (Principles of Plant 
Teratology, V. 1, p. 68) says: “The apogeotropie coralloid res- 
piratory roots of Cycads must probably be regarded as instances 
of normally fasciated roots.” The phenomenon of fasciation— 
flattening or banding—in the stems of plants, is a common oc- 
currence, but the expansion is usually the result of abnormal 
conditions. In the “Cocks-comb” (Celosia) this habit has been 
fixed by the horticulturist and the plants produce the flattened 
stem under normal conditions, though the expansion may be 
considerably increased by an excessively rich manurial diet. In 
a paper on Bacterial nodules, &e. (this journal, 2, 192), W. M. 
Carne drew attention to symbiosis in Cycadaceae, and referred 
to the work of Professor Bottomley. In a recent article deal- 
ing with this subject (Ann. of Bot., V. 29, p. 619), Ethel R. 
Spratt, supplements the Professor’s conclusions, and shows 
that all the Cycadean genera produce root nodules, which 
are perennial modified lateral roots, repeatedly branched, and 
typically forming large coralloid masses, and these structures 
are primarily produced by infection with Bacillus radicicola. 
The writer adds: “The Cyeadaceae . . . . are the only nodule- 
bearing plants known in which four organisms are associated 
symbiotically, viz., two nitrogen fixing bacteria, an alga, and 
the cycad.” The activities of bacteria when present in plant 
tissues are generally recognised as a potent stimulating factor 
in the production of fasciation. 
