Archaic, alternate and misspellings of words have been retained to match the original work with the exception of those listed below.
Missing punctuation has been added and obvious punctuation errors have been corrected.
Some page numbers have been removed to maintain text consistency.
Any reference to size, i.e. ½ nat. size, in the illustrations has not been retained.
Page 19: "gulley" changed to "gully" (on either side by a gully).
Page 51: footnote 78, added "p." (Spinden, p. 194.)
Page 82: "anterio" changed to "anterior" (leaving a large anterior lateral projection).
Page 92: "assymetrical" changed to "asymmetrical" (a slightly asymmetrical disk).
Page 93: illustration caption: "n" changed to "in" (in the collection of).