. The anatomical record. Anatomy; Anatomy. 84 Proceediuirs of the Association of American Anatomists from a specimen of Pterothrissus gissu (Hilgendorf) measuring cm. including caudal fin is here described for the first time. The conus arteriosus in Pterothrissus is plainly visible from the exterior although its base is, ventrally and to the right, to some extent buried in the ventricle. Dorsally and to the left the conus is in contact with visceral pericardium practically from end to end. The bulbus, which is not so dilated as is usual in teleosts, very slightly overlaps the adjacent por
. The anatomical record. Anatomy; Anatomy. 84 Proceediuirs of the Association of American Anatomists from a specimen of Pterothrissus gissu (Hilgendorf) measuring cm. including caudal fin is here described for the first time. The conus arteriosus in Pterothrissus is plainly visible from the exterior although its base is, ventrally and to the right, to some extent buried in the ventricle. Dorsally and to the left the conus is in contact with visceral pericardium practically from end to end. The bulbus, which is not so dilated as is usual in teleosts, very slightly overlaps the adjacent portion of the conns. The conus valves are arranged in two tiers, each tier having a right and left cusp meeting, when in apposition, at the mid-sagittal plane. The accompan3dng figure, showing the ventral surface of a frontal section (X 10) passing through the middle of the valves, indicates the general relations of the conus. The prodigious depth of the distal cusps as compared to the shallower correspond- ing cusps of Albnla, Megalops, and Tarpon, is the most remarkable feature in this heart, and strongly reminds one of the deep distal cusps in Amia. The conus is proportionately longer in Pteroth- rissus than in any other form of teleost. The average length of conus as compared with ventricle (measured from the apex to the root of conus) is as 1 to In ^legalops this proportion is 1 to 4 (judging from the figures given by Boaz the pro- portion is about the same or slightly less in Al- bula) ; in Tarpon the proportion is 1 to 4-5. The atrio-ventricular valve in Pterothrissus is Frontal soction of placcd to the left of the midline and has four the conus Arteriosus iu Pterothrissus. THE HEREDITARY NATURE OF VARIATION IN THE OSSIFICATION OF BONES. By J. W. Puyok. State College of Kentucky, Lexington, Kentucky. While investigating the time of the appearance of centers of ossification in the bones of the human bod}'^, I have made the following observations: First.—The p
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectanatomy, bookyear1906
