Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
mētālis, e, adj. [meta, III. 3], conical (post-class.): forma, Paul. ex Fest. s. v. tutulum, p. 335 Müll.
Hence, adv.: mētālĭ-ter, conically (post-class.): majus corpus ejus quo umbra metaliter jacitur, quam umbra ipsa, Mart. Cap. 8, § 859; id. 8, § 870.