Remarks on the. Genus Paradoxides of Brongniart. 341 
light to produce the effects of September or October. The electric 
change denoted by the fact that in the region of the lakes, thunder | 
rarely occurs after these phenomena become visible, and that these "4 
are usually accompanied or followed by the aurora, would seem to : 
render such a supposition probable. ¥ 
We have thrown out these hints—for we consider them nothing 
more—in the hope of directing the notice of other and more com- 
petent observers to the facts stated, and, if possible, thereby gaining 
a satisfactory solution of the splendid phenomena connected with our 
autumnal sunsets, (should the foregoing not be considered as such,) 
or should further observations show that any of the above premises 
or inferences have been founded in error. 
Otisco, November 8, 1837. 
Art. XVIII.—Some Remarks on the Genus Paradoxides of Brong- 
niart, and on the necessity of preserving the Genus Triarthrus, 
proposed in the Monograph of the Trilobites of North Amer- 
ica ; by Jacos Grezn, M. D., Professor of Chemistry in Jeffer- 
son Medical College. 
Tue genus Paradoxides, first proposed by Prof. Brongniart, and 
founded on a magnificent trilobite in M. DeFrance’s collection, has 
embarrassed tnost fossil zoologists who have attempted to make use 
of it in arranging and describing their specimens. ‘The late Pro- 
fessor Dalman, in his important memoir on the trilobites, published 
in the Transactions of the Swedish Academy, would not admit the 
genus as it now stands, into his work, but grouped some of the spe- 
cies included in it, under the generic name of Olenus. 
The animal remain in M. DeF'rance’s cabinet, is called by Prof. 
Brongniart Paradoxides spinulosus, and was the only Paradoxides 
which he had examined when his valuable work on the Trilobites 
first appeared. Dr. Wahlenberg’s fine figure of the old Linnean 
Entomolithus paradoxus, was so analogous in all its principal charac- 
ters to the fossil of DeFrance, that he not only did not hesitate to 
consider it another species of the same genus, but he gave the ge- 
neric name itself to this group, to preserve the memory of Linne’s 
singular relic. Nowif this genus had embraced those animals only, 
which exhibit, what its author considers, its essential characters, 
there would have been no difficulty on this subject. ‘These charac- 
Vou. XXXILI—No. 2. 44 
