Definition: Nieuwkoop and Faber stage 22; age 24 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Distinct protrusion of eyes. Initial groove between jaw- and gill-areas only at latero-dorsal side. Lateral and ventral outlines of embryo slightly concave. Anal opening displaced to ventral side. Vitelline membrane becoming wider. Length: 2.0 - 2.2 mm.