Here is information about various signatures that the artist Theodore Gegoux has been found to have used over his career.

Gegoux Signatures

Folks, Although Gegoux did not always sign his work, in today's art market the signature remains a common way to identify the artist.  Gegoux would often sign his work in dark places, with dark colors.  Many of his portraits in pastel crayon from the late 19th Century are signed in hand written script "Theo Gegoux pinx" with the date.  "pinx", I'm told, is latin for "he painted it".  
Gegoux's signatures can easily be missed as happened in May 2003 at Du Mouchelles of Detroit, Michigan.  A portrait of a woman was auctioned without any mention of the artist Gegoux.  This despite the hand written signature "Theo Gegoux 1892 pinx" visible in the dark background.  
Christies East reported one of Gegoux's script written initials as a "J", rather than his "T" in their Auction Catalog from October 25th, 1988.  The entry in Davenport's shows J. Gegoux, but "Carting Hay" was clearly done by Theo Gegoux.  
Happy hunting, but remember to look carefully and thoroughly for signatures.  
Here are some examples:
  
Theolsegoux   "Theo Gegoux Pinx"
Used for pastel on paper - seen between 1880 and 1899.
Hand written inscription from the Portrait of a Woman - 1894. 		   
Theolsegoux   "Theo Gegoux"
Used for crayon on paper - seen between 1880 and 1899.
Hand written inscription from the Portrait of a Young Man - 1897. 		   
Aunt Molly   "Theo Gegoux pinx"
Signature from Portrait of Aunt Molly - 1895. 		   
Woman Portrait   "Theo Gegoux pinx"
Signature from Portrait of Bertha Powell - 1896. 		   
theolsegoux Regarding the Davenport Gold Book 2004 listing for   Theolsegoux.  There is no such person.  Gegoux's cursive script signatures also caused the problem at Christie's East back in 1988.  See Davenport - Gegoux, J.    
Thelsegoux   "Theo Gegoux"
Hand written inscription from the Barron portrait - 1889. 		Military Officer   "T. Gegoux"
Signature from Portrait of a Military Officer - 1905.
Sunrise at Castle Rock   "T. Gegoux"
Signature from Sunrise at Castle Rock - 1925. 		   
Helen Flanders   "T. Gegoux"
Signature from Portrait of Hellen Flanders - 1906. 		   
Two Sisters   "T. Gegoux"
Signature from Portrait of Two Sisters - 1908. 		   
MacIntyre Range   "T. Gegoux"
Signature from MacIntyre Range. 		   
Baby Signature   "T. Gegoux"
Signature from Portrait of a Baby - 1905. 		   
Woman Portrait   "T. Gegoux"
Signature from Portrait of a Woman - 1880. 		   
Grapes   "T. Gegoux"
Signature from Bunch of Grapes - 1912. 		   
Abernethy Farm   "Theodore Gegoux"
Signature from the Abernethy Farm - 1920. 		   
Kimball   "T. Gegoux"
Signature from Kimball Portrait of - 1898. 		   
T. Gegoux   "T.Gegoux."
  From the painting Winter Scene, circa 1900. 		   
Theo Gegoux   "Theo Gegoux"
  From the painting Moonlight On Lake Ontario, dated 1884. 		   
Sincerely,
Theodore Gegoux III
Rancho Cucamonga
909-532-1906