STAGE 35/36 Age 2 d., 2 h.; length 5.3-6.0 mm.

Ext. Crit.: Stomodeal invagination roundish. Eye entirely black, choroid fissure nearly closed. *Formation of two gill rudiments*, anteriorone nipple-shaped. *Melanophores appearing on back*. Posterior outline of proctodeum still curved. *Length of tail bud about 3 x its breadth*. Beginning of hatching.

Int. Crit.: Supra- and infraorbital lateral line anlagen extending to eye; hyomandibular lateral line placodes proliferating on both sides of cement gland; dorsal and middle trunck lateral lines extending beyond pronephros. Inter-retinal part of n. opticus distinct; *n. trochlearis has reached m. obliquus superior*. Cavity of optic stalk obliterated; *beginning of differentiation of pars optica retinae*; lens cavity fully developed.

*About 36 post-otic somites formed*. Chambers of S-shaped heart distinct; *4^th, 5^th and dorsal part of 6^th aortic arches completed*; secondary vessels of 3^rd and 4^th aortic arches formed; *paired dorsal aortae united as median dorsal aorta; medial postcardinals united behind cloaca*; lateral head veins and musculo-abdominal veins formed. Rich blood supply of pronephros from cardinal veins; coelomic filter chamber and glomus extending over entire length of pronephros.

*Oro-pharyngeal cavity separated from gastro-duodenal cavity by high transversal ridge; first contact of ectoderm and entoderm in 5^th visceral pouch (formation of 3^rd branchial arch)*. *Horizontal ridge separating primary liver cavity from tracheal cavity*; the former opeing distally into sub-mesodermal space; *dorsal pancreas anlage indicated; canalis neuentericus occluded*.