A number of [New World warblers](https://en.wikipedia.org/wiki/New_World_warbler) seem to have genus names that end in the element -thlypis. It's been hard for me to find information about the etymology of this element; I found a few sources on the web that say that it comes from a Greek word θλυπις that referred to some kind of bird, but I can't find any detailed description of this word, only brief mentions of it. The Wikipedia article on the "[Common yellowthroat](https://en.wikipedia.org/wiki/Common_yellowthroat)" says 

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> The genus name Geothlypis is from Ancient Greek geo, "ground", and thlupis, an unidentified small bird; thlypis is often used in the scientific names of New World warblers.
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The *[Helm Dictionary of Scientific Bird Names](https://books.google.com/books?id=-RfSBAAAQBAJ&pg=PA154),* by James A. Jobling, seems to corroborate this statement:

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> **Euthlypis** Gr *eu* fine, good; *thlupis* unknown small bird, perhaps some sort of finch or warbler. In ornithology *thlypis* signifies either a parulid warbler or a thin-billed tanager.
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I'd like to know where exactly θλυπις occurs in Greek texts, and whether we know anything more about the word than its spelling and the vague idea of its meaning that is described in these quotations. For example, do we know how it is declined, or the length of either of the vowels? I couldn't find this word in any online dictionaries of Greek.