I recently came across the term "triangle given in species" in Hatton's Projective Geometry. Searching in archive.org turned up other examples (such as this) of 19th century texts, and it is also used in Euclid. But I don't see it defined anywhere. By context, I think it refers to similar triangles, but it would be nice to see a definition somewhere. Also, does it have a meaning wider than "similar" in geometry?
III. Rectilineal figures are said to be given in species, which have each of their angles given, and the ratios of their sides given. (English version, R. Simpson, 1810, p. 367)
[Species is the translation of eidos, shape or form; see LSJ, εἶδος, def. A.2.b.]