Gutta

At the top of the architrave blocks, a row of six guttae below the narrow projection of the taenia (fillet) formed an element called a regula.

[1] It is thought that the guttae were a skeuomorphic representation of the pegs used in the construction of the wooden structures that preceded the familiar Greek architecture in stone.

[3] In the strict tradition of classical architecture, a set of guttae always go with a triglyph above (and vice versa), and the pair of features are only found in entablatures using the Doric order.

The Doric order of the Villa Lante al Gianicolo in Rome, an early work of Giulio Romano (1520–21), has a narrow "simplified entablature" with guttae but no tryglyphs.

[5] The Baroque Černín Palace in Prague (1660s) has triglyphs and guttae as ornaments at the top of arches, in a facade using an eclectic Ionic order.