Some Louisiana Landrys are descendants of a third line to have settled in the state. This third line is that of Jean Jacques Landry and his wife Susanne Sandoz from Neuchatel, Switzerland, who settled in St. Martinville in the 1830's. Jean Jacques was born in 1805, married in St. Martinville in 1831, and died in 1861. Records show that Jean and Susanne had seven children;
- Suzanne
- Louis Joseph
- Aimee Desire
- Anne Desire
- Modeste
- Alida
- Henri
Aime Desire Landry who married in 1859 to Sarah Ann Whittingham, daughter of James Alexander Whittington and Sarah Ann Sellers, had ten children;
- Louis Robert 1860
- Arthur 1861
- Aimee Jr. 1862
- Marie Serianne 1865
- Clothilde 1866
- Felix Robin 1868
- Juan Henry 1869
- Alice Louise 1871
- Anne Philomene 1873
- Angele 1876
These families established themselves in the Lafayette area.
Henri Fredrick Landry married in 1865 to Felicite Billeaud. Their sons also established themselves in Lafayette Parish, where they had four (4) sons and five (5) daughters. They raised their families in Lafayette parish where most of their pogeny live today.