EXTREME or total microglossia is comparatively rare. This anomaly can be attributed to failure of the anterior two-thirds of the tongue to form following agenesis of the first mandibular process, which is derived from the first and second branchial arches at the time when these structures fuse ventrally during about the fourth week of intrauterine life. By the seventh week a small median swelling, the tuberculum impar, arises at the point of fusion and, in turn, fuses with an elevation from the first mandibular process on each side, forming the anterior two-thirds of the tongue. The posterior third of the tongue is formed from the mesoderm of the third pharyngeal arch which grows forward as a V-shaped process from the anterior part of the hypobranchial eminence. The line of fusion of the anterior and posterior parts of the tongue is V-shaped and is indicated in the adult by the vallate papil1ae.l A receding chin, congenital absence of incisors, a constricted mandible, and a sharp and narrow face, described as Vogel gesicht, may be associated with the branchial-arch deficiency or may be unrelated to the microglossia.’ In infants with microglossia or aglossia, hypertrophy of the structures in the anterior part of the floor of the mouth increases effectiveness in deglutition. This hypertrophy can be ascribed to the soft tissues’ compensatory attempts at compression against the hard palate in swallowing when t,he t,ongue itself is of insufficient size (Fig. 1).