This is either a transcription error or a deliberate corruption that was changed in other editions. In various versions of the text you can find on the web, for example, in a lesson in the Holt Elements of Literature, the quote is rendered
I hunt the scum of the earth—sailors from tramp ships—lascars, blacks, Chinese,
whites, mongrels—a thoroughbred horse or hound is worth more than a score of them.
That same source identifies lascar as an East Indian sailor employed on a European ship. The OED defines a lascar or Lascar more broadly as any East Indian sailor, tracing it to an erroneous European use of the Urdu lashkar or lashkari, dating in English to about 1625.