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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
EXPLANATION OF PLATE LVII. 
Fig. 44. Side view of cranium of the common sturgeon, modified from Wiedersheim. 
Fig. 45. Dorsal view of dermal armati.ie of the head of the common sturgeon, modified from Gageu- 
baur. 
Fig. 46. Mandibles and palatopterygoid of the young sturgeon with its musculature. 
Fig. 47. Cross-section through the spiral valve of the intestine of A. brevirostris, showing the manner 
of flexure of the spiral fold N F, and the large lymphoid cord L at its margin in section. The 
fold itself is covered with villi as well as the intestinal wall. Enlarged three diameters. 
Fig. 48. Pyloric end of stomach, pylorus, and duodenum laid open so as to display the three openings 
into the latter from the pancreas. 
Fig. 49. Figures representing the cartilaginous elements of the ventral fins of Acipvnser brevirostris. 
Fig. 50. Figure of the cartilages of the right pectoral fin of a young specimen of Acipenser sturio. 
