Z ART. 7. — S. TANAKA : 



the Science College Museum and partly in Mr. Alan 

 Owston's collection (Yokohama). A few were taken from other 

 sources. 



All the measurements of the specimens in this paper are in 

 centimetres. 



I wish here to express my thanks to Dr. C. H. Gilbert, 

 of the Leland Stanford University, to Professor K. Mitsukuri 

 and to Professor I. Ijima, to all of whom I am deeply indebted 

 for many valuable help rendered me during my studies and in 

 the preparation of the manuscript. In no less degree are my 

 thanks due to Mr. Alan Owston for the loan of his valuable 

 specimens. 



Tetronarcine tokioms, n. sp. 



Disc roundish. Eye small. Spiracles oblong, at a distance 

 less than their longitudinal diameter or less than twice eye 

 length behind eye ; margin of spiracle even, not fringed. Origin 

 of first dorsal anterior to posterior end of ventral, but less than 

 half the base of the dorsal opposite to the ventral ; first dorsal 

 more than twice the second in size. Ventrals separate. Free 

 margin of caudal emarginate ; its upper and lower lobes about 

 equal to each other, or the former a little larger than the 

 latter. A longitudinal fold of skin runs on the lower part of 

 side of body from before origin of second dorsal to beyond base 

 of caudal. Mouth small ; its breadth slightly greater than its 

 distance from tip of snout. Teeth on the jaws in several rows ; 

 each tooth with a sharp point. Anterior nasal valves confluent 

 into a quadrangular lobe. Skin perfectly smooth. 



