150 ART. 2. — H. MATSUMOTO : 



stout, with well developed lateral wings for the attachment of 

 voluminous masticatory muscles. The oral and dental plates are 

 very stout in internal view, the two presenting an X- shape. One 

 to six oral papilte on either side, the innermost one being often 

 infradental. Teeth very stout, widened, squarish, with wavy or 

 notched cutting ends. Arras inserted ventrally to the disk, 

 horizontally flexible, or rarely capable of coiling vertically. Dorsal 

 side of the vertebrae entire, not strongly notched inwards. Vertebral 

 articulation zygospondyline, the articular peg being always present. 

 Arm spines moderately long, conical, stout, opaque. Usually 

 one or two leaf-like tentacle scales, sometimes none. 



The present family includes eighteen genera, which may be 

 grouped into two subfamilies as follows. 



Subfamily 1. Ophiactinince Matsumoto, 1915 : — No paired 

 infradental papillae. 



Ophiactis Lütken, 1856. 

 Hemipholis (Agassiz) Lyman, 1865. 

 Ophiopus Ljungman, 1866. 

 Ophiopholis Müller & Teoschel, 1842. 

 Subfamily 2. Amphiurince mihi, 1915 : — Paired infradental 

 papillae present. 



I. Four or more oral papillae on either side, the outermost 

 one or two arising from the adorai shield ; one additional 

 papilla is present just outside and above the infradental 

 one ; oral shts closed by the oral papillae. 

 Ampliioplus Veerill, 1899. 

 Amphichilus, nov. 

 Amphiacantha, nov. 

 Ampliilimna Yeerill, 1899. 

 II. Three, rarely four, oral papillae on either side, none 



