Wissenschaftliche Ergebnisse der Deutschen Tiefsee-Expedition auf dem Dampfer "Valdivia" 1898-1899..Jena,G. Fischer,1902-40..biodiversitylibrary.org/page/6002204
The South Amerian River Stingray is locally known as Raya del Rio and feared by those walking bare-footed through drainages of the Western Amazon. In context at www.dixpix.ca/Amazon/fauna/riverlife/index.html