VOL. XXX. 



398 PROCEEDINGS OF THE NATIONAL MUSEUM. 



Bay. It is distinguished from most other sturgeons by the very long 



dorsal fin. ^ ^, t • i 



(Named for Prof. Dairoku Kikuchi, late president of the Imperial 



University of Tokyo.) 



ACIPENSER MIKADOI Hilgendorf. 

 CHOZAME (CHIEF SHARK). 

 iemenser mikadoi Hilgendorf, Sitz. Naturf. Freunde Berlin, 1901, p. 98: Tokyo 

 market, doubtless from Hokkaido.— Jordan and Snyder, Journ. Coll. Sci. 

 Tokyo,' 1901, p. 303: Ishikari R., Teshio, Mikawa.— Schmidt, Pise. Mar. 

 Orieiit, 1904, p. 284: Hakodate, etc. 

 Head, 3f to 3| in length; depth, 6i to 7. Snout, 2 to 2tV in l^ead. 

 Dorsal plates, 7 or 8; lateral, 34; ventral, 9. Dorsal rays, IV, 31 to 

 IV, 36; anal rays, III, 25 to III, 28. 



Top of head, bony; snout, short, rather sharp; cheeks with rough 

 plates; opercle, rugose. Sides above, between series of large plates, 

 with smaller plates mostly stellate, U of these forming an irregular 

 row below the dorsal series; plates, well keeled, with radiating strife, 

 rather than rugose; 4 to 6 plates behind dorsal; 2 to 4 behind anal. 

 Pectoral, | in head; height of dorsal, 3i; uppei- lobe of caudal, li 



in head. 



Described from three examples in the Imperial Museum ot lokyo, 

 each about U meters in length, the lirst from the Ishigari River, in 

 Hokkaido, the others from streams in Teshio and Mikawa, -ill of these 

 localities being in the island of Hokkaido. This is the common stur- 

 geon of northern Japan, known as chozame or chief shark. 



(Mikado, the emperor of Japan.) 



