1. Visit https://docs.mongodb.com/master/reference/operator/query/type/#available-types
2. Check you are on v3.4 (Upcoming)
3. The decimal128 type ('19' or '\x13') row and decimal alias is missing

This available types page should also note that the decimal128 type was added in 3.4 and link to https://docs.mongodb.com/master/release-notes/3.4/#decimal-type

See also http://bsonspec.org/spec.html