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ME. GEOEGE W. CALLENDEE ON THE EOEMATION OF 
Explanation of the Plate. 
PLATE I. 
Eig. 1. Subaxial and exoccipital arches in a foetus (*45 of an inch long), x 6. 
Fig. 2. Lingual, hyoid, and laryngeal arches, with the thyroid body, in a foetus -9 of an 
inch long. X 6. 
Fig. 3. The same arches as in fig. 2, with the addition of the mandibular. The divisions 
of the hyoid and laryngeal arches are shown, and also the connexion of the 
lingual arch with cartilage and membrane at the base and side of the skull. 
From a foetus 1*2 of an inch long. X 6. 
Fig. 4. The same arches at a more advanced stage, from a foetus L4 of an inch long. 
X 6. The anterior portion of the lingual arch has been removed. 
Fig. 5. The same structures, including the lingual arch, in a foetus L8 of an inch long. 
X 6. 
Fig. 6. Ridges seen on the inner surface of the exoccipital arch in a foetus '45 of an inch 
long. X 6. 
Fig. 7. Outer surface of the exoccipital arch, showing the division of its lower border 
into the clavicular and scapular rods, and the growth beneath these of the 
sternum and ribs. From a foetus *55 of an inch long. X 6. 
Fig. 8. Dorsal and ventral surfaces of the scapula of a foetus *9 of an inch long. x6. 
Fig. 9. The same surfaces of the scapula of a foetus 1*2 of an inch long. In this and 
in the preceding figure the anterior surface of the clavicle is also represented. 
X 6. 
Fig. 10. Dorsal surface of the scapula of a foetus 1’8 of an inch long, showing the out- 
growth of the glenoid cavity and of the coracoid plate, x 6. 
Explanation of Abbreviations. 
a. Acromion. 
ar. Arytenoid cartilage. 
c. Clavicle. 
c m. Constrictor muscles of pharynx. 
co. Coracoid process. 
co.]). Coracoid plate of scapula. 
cr. Cricoid cartilage. 
g. Glenoid cavity and border. 
h. Hyoid arch. 
h*. Posterior extremity of the cartilage of the hyoid arch. 
