MONOGRAPH OF JAPANESE OPHIUROIDEA. Bll 



divisions of Ophioconis s. ext,, together with certain aUied genera, 

 are distinguished as follows. 



A — Arm spines long and flagellate, erect. 



a — Outermost oral papilla very large and operculiform ; peristomial 

 plates simple, verj short and wide, the two halves being soldered 



together fairly well, Avithout median secondary plate 



Ophiolimna, emend. 



aa— Outermost oral papilla pointed inwards, projecting above the next 

 papilla, which is the largest; peristomial plates triple, with a 

 median secondary plate, fairly long and wide. 

 h — Oral shields entirely covered with granules ; arm plates usually 



concentrically striated ; arm spines hyaline, 

 c — Teeth triangular and pointed, ventral arm plates wider than long, 



usually separated from one another OpMuroconis. 



cc — Teeth flat, thin, with much widened and often serrate end ; ventral 



arm plati s longer than wide, in contact Avith one another 



. ; .- Ophiiirodon. 



lb — Oral shields naked ; arm plates not concentrically striated ; arm 



spines opaque. 

 d — Disk granulations mingled with a number of spines ; accessory oral 



shields absent Ophmrochœta . 



dd — Disk free of spines ; accessory oral shields usually present just out- 

 side the ordinary ones Opidarachia . 



AA — Arm spines very shoi-t, lying flat on the arm, hyaline. 



e — Oral shields entirely covered A^ith granules Ophioconis, restr. 



ee — Oral shields naked '' Ophioconis " indica. 



OjyJiioiimna emend, is il typical nienaber of the Ophiacanthidce ; 

 Ophiuroconi's, Ophiurodon, Ophiurochceta and Ophiarachna form the 

 Ophiaraclmince ; and Ophioconis restr. and " OpJnoconis " indica are 

 referable to the Ophiodei^mcdinœ. Oplnoconis restr. is very near to 

 Cryptopelta, but differs from it in the hyaline arm spines, while 

 " Ophioconis'' indica resembles Pectinura, differing from it also in 



