emma A ih a ls aca ala cas 
Zoology anid Botany. 75 
That the shape and arrangement of the bones follow, of 
8 
any alterations, however slight, in any part of the 
combination of bones, muscles, and joints, would entail a loss of 
f 
support to the postulate, that the similarities found to exist in the 
ones, muscles, and joints of animals may be explained by com- 
mon descent fron a supposed common ancestor. 
With respect to muscular action Dr. Haughton lays down these 
three laws: 
Law IL—In comparing together different muscles, the work 
done in contracting is proportional to the weight of each. 
Law IL—In comparing the same muscle (or group of muscles) 
with itself, when contracting under different external conditions, 
the work done is always constant in a single contraction. 
Law III.—When the same muscle (or group of muscles) is ae 
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in Mann’s Catalogue, the additional species being mar ed by 
letters added to the nearest number. The whole ; 
tinct species recognized is 126, besides which there are given 12 
named varieties. Since the list was printed an additional species 
has been reported, viz: Aspidium unitum Mettenius, found near 
Enterprise, Florida, by Mr. C. E. Faxon of Cambridge, Mass. 
containing three limited families, which are neatly elaborated by 
. Engler of Munich; viz: Olacinewe, with 8 plates, one of t 
