SOME ADDITIONAL DATA ON THE POSITION 
OF THE SACRUM IN NECTURUS. 
FRANK SMITH. 
THREE papers! which deal incidentally with the position of 
the sacrum in Necturus maculosus Raf. have appeared within 
recent years, in each of which are mentioned several instances 
of variation from the typical symmetrical sacrum on the nine- 
teenth vertebra, and they record observations on 158 speci- 
mens. The use of W. maculosus as an object of study in some 
of the zodlogical classes of the University of Illinois has made 
it easy to accumulate additional information on the position 
of the sacrum in this species, and since data of this kind have 
a recognized value, and since certain variations from the normal 
condition have been found which have not been previously 
reported, it seems worth while to publish a brief account of 
the relations of the sacrum in the 114 specimens which have 
been examined in our laboratories. The material was all ob- 
tained from Lake Erie, near Sandusky, Ohio, during the years 
1897-99. / 
Table I presents in a convenient form the data from the 
above-mentioned specimens, but as thirty-two of them were not 
examined for the position of the first haemal arch they are 
tabulated in a separate column. 
For convenience in a comparison of the various observations 
mentioned, Table II has been prepared. It relates to 241 speci- 
mens — the 158 specimens previously recorded, the eighty-two 
Specimens listed in Table I, in which the position of the first 
haemal arch is known, and one other specimen listed in that 
1 Parker, G. H. Variations in the Vertebral Column of Necturus, Anat. 
Anzeiger, Bd. xi, pp. 711-717. 
umpus, H. C. A Contribution to the Study of Variation (Skeletal Variations 
of Necturus maculatus Raf.), Journ. of Morph., vol. xii, pp. 4 55-484, 3 pls. 
Waite, F.C. Variations in the Brachial and Lumbro-Sacral Plexi of Necturus 
maculosus Raf., Bull. Mus. Comp. Zoöl., vol. xxxi, No. 4, pp. 71-92, 2 pls. 
635 
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