i 
_ which would indicate that they are shed like teeth, together 
848 | General Notes. 
the denticles, the segmented character of the fossils, and 
fact that the segments are found singly, and of different 
the presence of a slender curved basal bone (similar to that it 
Onychodus of the Devonian of Ohio) in the Australian fom 
described by Dr. Woodward, led the author to think that thet 
fossils are neither dorsal spines nor pectoral fins, but intermate 
dibular teeth, which had a membranous or cartilaginous suppot 
in the American forms, and an osseous support in the Au a 
These supports would bear the same relation to the mandibula 
arch that the glosso-hyal does to the hyoid arch —Fanny R M 
Hitchcock. : E 
MINERALOGY AND PETROGRAPHY: 
The rocks of the island Heard are very similar to those 
In the neighborhood of Corinthian Bay the prevailing f 
a feldspathic bas townite 
grouped together like the chondra of meteoric stones. 
YOR to the basalts there occur on the island trachites, lim 
i phonolites, Of these the trachytes and phonolites 
an the basalts—T wo late articles on the petrogt of this 
Tyrol add several interesting facts to our knowledge % 
* Edited by Dr. W. S. BAYLEY, Madison, Wisconsin. 
i Ui 
? American Naturalist, Notes, 1886, p. 640 
3 Bull. d. 1. Soc. Roy. de Belg., 1886, iii. p. 245- ~ 
