SCAPANORHYNCHUS OWSTONI. 29 



symphysis is curved upward and is without or with teeth that are much smaller 

 than those at either side of it. Spiracle small, less than half the diameter of the 

 eye, behind the orbit, sometimes absent on one side, perhaps on both sides. 

 Gill openings wide, at least three times the width of the orbit, hindmost above 

 the pectoral. All fins rounded on their extremities, longer than wide, and 

 covered by shagreen. Pectorals medium, reaching below the middle of the base 

 of the dorsal. Dorsal origin behind the base of the pectoral, above the hinder 

 half of the fin extremity; end reaching a vertical from the ventrals; fin smaller 

 than the pectoral, rather narrow, in height less than the length of the base. 

 Ventrals larger than the pectorals, equal to the anal, below the space between the 

 dorsals, reaching a vertical from the second dorsal. Second dorsal little longer 

 than the first, base little shorter, end reaching beyond the middle of the anal base; 

 base equal two sevenths of the interdorsal space or two fifths of the distance 

 from the caudal. Anal large, base subtending two fifths of that of the second 

 dorsal, as long as the bases of the ventrals, ending close to the subcaudal. Caudal 

 nearly one third of the total length, deep anteriorly, without a produced sub- 

 caudal lobe, subcaudal followed by a shallow notch at the edge of the terminal; 

 vertebral axis of fin very slightly raised. Lateral line distinct, pores small, 

 line nearly straight behind the aural region, descending little on the side of the 

 muscular portion of the tail, resembling that of Carcharias taurus. Claspers 

 slender, pointed, reaching one and one-half inches behind the origin of the anal, 

 slit for about six inches, that is from the base of the ventral to within an inch 

 of the end of the organs. 



Total length of an adult male 104, snout to abdominal pores 53, snout to 

 first dorsal 36, snout to fifth gill opening 28, snout to skull 10^, length of caudal 

 34 inches. 



Greyish brown, lighter and rust-colored on lower surfaces, darker toward 

 the margins of the fins. 



Plate 51 contains a view of a longitudinal section of the skull, a drawing of 

 the branchial cartilages from above and from below, another of the heart and 

 arterial branches, and a section of the spiral intestine as compared with that of 

 Carcharias taurus, and on Plate 56, figure 2 shows the arrangement of the valves 

 in the bulbus. 



Sagami Sea, Japan. Specimens, large and small, from Mr. Alan Owston. 



