Fig. 1. Progne subis. Lateral view of left half of thorax. M. pectoralis thoracica (area of insertion indicated by dotted line) has been removed. Muscles not described in text are not shown. (× 1.5.) Fig. 1. Progne subis. Lateral view of left half of thorax. M. pectoralis thoracica (area of insertion indicated by dotted line) has been removed. Muscles not described in text are not shown. (× 1.5.)
Fig. 2. Progne subis. Lateral view of left half of thorax. Same view as shown in Fig. 1, but with Mm. supracoracoideus, coracobrachialis posterior, and intercostales externus removed. (× 1.5.) Fig. 2. Progne subis. Lateral view of left half of thorax. Same view as shown in Fig. 1, but with Mm. supracoracoideus, coracobrachialis posterior, and intercostales externus removed. (× 1.5.)

Fig. 3. Progne subis. Medial view of left half of thorax. Not all muscles shown. See Fig. 4 for identification of arteries. (× 1.5.) Fig. 3. Progne subis. Medial view of left half of thorax. Not all muscles shown. See Fig. 4 for identification of arteries. (× 1.5.)
Fig. 4. Progne subis. Lateral view of left half of thorax. (× 1.5.) Fig. 4. Progne subis. Lateral view of left half of thorax. (× 1.5.)

(Applies also to Fig. 3.)

1. Subclavian artery.
 2. Coracoid artery.
 3. Thoracic artery.
 4. (Unnamed.) Supplies M. coracobrachialis posterior.
 5. (Unnamed.) Supplies M. subcoracoideus.
 6. (Unnamed.) Supplies M. sternocoracoideus and sternum.
 7. (Unnamed.) Supplies M. subcoracoideus.
 8. (Unnamed.) Supplies M. sternocoracoideus, M. coracobrachialis posterior, and sternum.
 9. Pectoral artery.
 10. Axilliary artery.
 11. (Unnamed.) Supplies M. coracobrachialis posterior.
 12. (Unnamed.) Supplies M. supracoracoideus.
 13. (Unnamed.) Supplies M. costi-sternalis anterior.
 14. Carotid artery.

Fig. 5. Scardafella inca. Lateral view of left half of thorax. M. pectoralis thoracica (area of insertion indicated by dotted line) has been removed. Muscles not described in text are not shown. See legend for Fig. 7 for identification of arteries. (× 1.) Fig. 5. Scardafella inca. Lateral view of left half of thorax. M. pectoralis thoracica (area of insertion indicated by dotted line) has been removed. Muscles not described in text are not shown. See legend for Fig. 7 for identification of arteries. (× 1.)
Fig. 6. Scardafella inca. Lateral view of left half of thorax. See legend for Fig. 7 for identification of arteries. (× 1.) Fig. 6. Scardafella inca. Lateral view of left half of thorax. See legend for Fig. 7 for identification of arteries. (× 1.)

Fig. 7. Scardafella inca. Medial view of left half of thorax. (× 1.) Fig. 7. Scardafella inca. Medial view of left half of thorax. (× 1.)

Key

(Applies also to Figs. 5 and 6.) Numerals not used are those used for Progne subis for which no homologous artery occurs in Scardafella inca.

1. Subclavian artery.
 2. Coracoid artery.
 3. Thoracic artery.
 4. (Unnamed.) Supplies Mm. coracobrachialis posterior and sternocoracoideus.
 4a. (Unnamed.) Supplies M. coracobrachialis posterior.
 6. Sternal artery. (Shown as it appears on right side. Left sternal artery not so extensive.)
 6a. (Unnamed.) Supplies M. sternocoracoideus.
 7. (Unnamed.) Supplies M. subcoracoideus.
 8. (Unnamed.) Supplies coracoid-sternal articulation.
 9. Pectoral artery.
 10. Axillary artery.
 12. (Unnamed.) Supplies M. supracoracoideus.
 14. Carotid artery.
 15. (Unnamed.) Supplies M. supracoracoideus.

LITERATURE CITED

American Ornithologists' Union

1957. Check-List of North American birds. Baltimore, Maryland, Amer. Ornith. Union, xiv + 691 pp.

Ashley, J. F.

1941. A study of the structure of the humerus in the Corvidae. Condor, 43:184-195.

Beddard, F. E.

1898. The structure and classification of birds. London, Longmans, Green, & Co., xx + 548 pp.

Berger, A. J.

1956. Anatomical variation and avian anatomy. Condor, 58:433-441.

Bhaduri, J. L., and Biswas, B.

1954. The main cervical and thoracic arteries of birds. Series 2. Columbiformes, Columbidae, part 1. Anat. Anz., 100:337-350.

Bhaduri, J. L., Biswas, B., and Das, S. K.

1957. The arterial system of the domestic pigeon (Columba livia Gmelin). Anat. Anz., 104:1-14.

Coues, E.

1903. Key to North American birds. Vol. I, Fifth edit. Boston, The Page Company, xlii + 535 + [55] pp.

Fisher, H. I.

1955. Major arteries near the heart in the Whooping Crane. Condor, 57:286-289.

Glenny, F. H.

1940. The main arteries in the region of the heart of three species of doves. Bull. Fan Mem. Inst. Biol., Zool. ser., vol. 10, pt. 4, 271-278. (Not seen.)

1955. Modifications of pattern in the aortic arch system of birds and their phylogenetic significance. Proc. U. S. Nat. Mus., 104:525-621.

Howard, H.

1929. The avifauna of Emeryville Shellmound. Univ. Calif. Publs. Zool., 32:301-394.

Howell, A. B.

1937. Morphogenesis of the shoulder architecture: Aves. Auk, 54:364-375.

Hudson, G. E., and Lanzillotti, P. J.

1955. Gross anatomy of the wing muscles in the family Corvidae. Amer. Midl. Nat., 53:1-44.

Mayr, E.

1955. Comments on some recent studies of song bird phylogeny. Wilson Bull., 67:33-44.

Mayr, E., Linsley, E. G., and Usinger, R. L.

1953. Methods and principles of systematic zoology. New York, McGraw-Hill Book Co., x + 336 pp.

Simpson, G. G.

1961. Principles of animal taxonomy. New York, Columbia Univ. Press, xiv + 247 pp.

Transmitted June 24, 1963.