No. 2.] EARLY DEVELOPMENT OF AMBLYSTOMA. 409 



REFERENCE LETTERS. 



a. Anus. 



bp. Blastopore. 



ch. Chorda. 



c.k. Caudal knob. 



c.v. Caudal vesicle. 



c.v! Secondary caudal vesicle. 



dl. Dorsal lip of blastopore. 



ep. Epiblast. 



g.c. Gastral cavity. 



g.r. Germ-ring. 



hy. Hypoblast. 



K.v. Kupffer's vesicle. 



m. Mesoblast anlage. 



mes. Mesoblast. 



n.f. Neural folds. 



n.g. Neural groove. 



n.p. Neuropore. 



o.g. Oral groove. 



olg. Olfactory groove. 



o.p. Optic pits. 



per. Periblast. 



S.C. Segmentation cavity. 



s.ep. Sensory epiblast. 



tel. Teloblast. 



»./. Vegetative pole. 



yk. Yolk. 



yp. Yolk plug. 



