ZOOLOGY: W. M. WHEELER 
109 
probably colorless pyroxene, possibly jadeite. This tinguatic phonolite 
forms fissile massive bodies, having a chemical composition shown by 
analyses 4 and 5; one from south of Limpang Kopeng in the east cen- 
tral part of the island, the other from a southwest spur of the central 
mountain, Gunung Besar. 
Other phonolitic rocks have a trachytoid groundmass of prismoid 
alkaHc feldspars with small leucites in some varieties, and minute en- 
hedral sodalites in others. Still fewer are trachytes with almost no 
recognizable feldspathoid constituent. 
Analysis 6 is of a sodalite-trachyte which appears to contain some 
kaolinite, but the thin section does not show the presence of any hy- 
drous mineral. The chlorine in the analysis corresponds to 8% of 
sodalite. 
The rocks from Bawean so far analyzed are strongly alkalic, with 
relatively high potash in the vicoites. They are chemically similar 
to the leucitic rocks of Mount Mourah in Java, and to the leucitic and 
nephelitic rocks of the Maros district in Celebes, but they differ in 
petrographical characters from the rocks of both these districts. 
THE PHYLOGENETIC DEVELOPMENT OF SUBAPTEROUS AND 
APTEROUS CASTES IN THE FORMICIDAE 
By William Morton Wheeler 
BUSSEY INSTITUTION. HARVARD UNIVERSITY 
Read before the Academy, November 14. 1916 
It is generally admitted that each of the four groups of social insects — 
the social bees, social wasps, ants and termites — has had an independent 
phyletic origin and history and that the similarities in their habits are 
due to parallelism, or convergence, of which, indeed, they exhibit strik- 
ing examples. In both the fertile and sterile females of social wasps 
and bees the wings show no signs of reduction, whereas these appen- 
dages are well-developed in the fertile females (females proper) of the 
great majority of ants, at least prior to fecundation, but are normally 
always absent in the sterile females, or workers. Paleontology proves 
that identical conditions have long existed in the Formicidae as a fam- 
ily, since they are clearly shown in the abundant and beautifully pre- 
served ants of the Baltic amber from the Lower Oligocene Tertiary. ^ 
Writers also agree that the ants must be descended from certain 
