The Silhouette Glabrennea Snail was described in 1994, it restricted to a very small area on Mt. Dauban on the island of Silhouette, Seychelles Islands, when it was discovered in 1990.
The species apparently was an inhabitant of leaf litter.
The Silhouette Glabrennea Snail was only ever found at its type locality, once in 1990, and a for second time one year later in 1991, when its population was already declining. All subsequent searches (2000, 2009, 2010) at the type locality and other suitable areas failed to find the species again which thus is considered extinct. 
 Justin Gerlach: Red List ing reveals the true state of biodiversity: a comprehensive assessment of Seychelles biodiversity. Phesluma 20: 9-22. 2012  Justin Gerlach: Changes in non-marine mollusc populations in the Seychelles islands 1986-2012. Phelsuma 20: 23-38-2012
This species was described in 1921, it is apparently known from only four specimens that were collected on the islands of Mahé and Silhouette, Seychelles Islands.
The last specimen, a male, was obviously collected in 1969, since that date there has not been any trace of this species, which is now feared to be extinct.
 Pat Matyot: The hawkmoths (Lepidoptera: Sphingidae) of Seychelles: identification, historical background, distribution, food plants and ecologiclal considerations. Phelsuma 13. 55-80. 2005
 Justin Gerlach: Red List ing reveals the true state of biodiversity: a comprehensive assessment of Seychelles biodiversity. Phesluma 20: 9-22. 2012
The Seychelles Parakeet was described in 1867, it was already very rare at that time and restricted to only two islands in the Seychelles, Mahé and Silhouette, it might formerly have occurred on all of the islands.
The species was closest related to the Alexandrine Parakeet (Palaeornis eupatria (L.)) from which it differed mainly by the lack of a rose-colored neck collar; it was formerly also merged with that species.
The Seychelles Parakeet was last recorded in 1883 when the last known specimen died in captivity, the species died out because it was heavily hunted for being a ‘pest’ to crops.
Marianne North, a botanical artist, depicted a live pair of this species on the island of Mahé when she visited the family of Dr. James Brooks, a colonial medical officer on the Seychelles. She also wrote some notes about these two birds:
“He and his Greek wife were very kind and hospitable in their offers to me. I went one day to their house, and painted their parrots, which came originally from Silhouette: queer, misshapen birds, with enormous beaks and patches of red and yellow badly put on, one of them having a black ring round its neck. Both were quite helplessly bullied by common pigeons, which came and ate up their food, while they jabbered in a melancholy way, and submitted. They had absolutely no tops to their heads, which perhaps accounted for their stupidity. They had a stand on the back verandah, where they slept and were fed. They were not tied up, but went and stole their own fruit off the neighbouring trees.” 
 Anthony S. Cheke: Animals depicted by Marianne North in her Seychelles paintings. Phelsuma 21: 47-57. 2013  Michael P. Braun; Thomas Datzmann, Thomas Arndt; Matthias Reinschmidt; Heinz Schnittker; Norbert Bahr; Hedwig Sauer-Günth; Michael Wink: A molecular phylogeny of the genus Psittacula sensu lato (Aves: Psittaciformes: Psittacidae: Psittacula, Psittinus, Tanygnathus, †Mascarinus) with taxonomic implications. Zootaxa 4563(3): 547-562. 2019