y Q NATURAL HISTORY BULLETIN. 



Family. HEMIEURYALID^E Ver. 



In this family are included several genera of true Ophiurae, 

 which very much resemble, in form and habits, the simple- 

 armed Euryalae or Astrophytons. Like the latter, they coil 

 their arms closely around the branches of gorgonian corals 

 on which they dwell. 



The disk is pentagonal and covered with thick plates or 

 tubercles, which may be conical. The radial shields are large 

 and prominent. 



Upper arm-plates may be entire and accompanied by sup- 

 plementary plates, or they may be replaced by a mosaic of 

 small plates. They are thick or tubercular. 



Under arm-plates well formed. Side-plates separated by 



extra plates. Oral and adoral shields normal. Spines few, 



short and stumpy. A row of mouth papillae. Teeth, but no 

 definite cluster of tooth-papillae. 



Genital pores small, situated near together at the outer end 

 of the oral shield. Arm-bones have special forms approach- 

 ing those of the Astrophytons. Mouth-frames strongly ossi- 

 fied. 



The genera belonging to this family, are Hemieuryale, 

 Ophioplus, and Sigsbeia. 



Ophioplus, gen. nov. 



Type, Hemieuryale tuberculosa Lyman. 



Plate I; Figures i. la, ib. 

 Disk small, pentagonal, thick, covered with small, thick- 

 ened or tubercular scales. Radial shields large, naked, sep- 

 arated. Oral shields and adoral shields well developed and 

 naked. Mouth-papillae in regular series. No tooth-papillae. 

 Under arm-plates rather large. Upper arm-plates entire, 

 swollen and well formed, separated by a transverse row of 

 small, tubercle-like plates. Side arm-plates prominent, 

 separated above by a supplementary lateral plate. Arm- 

 spines short, two or three in a row. Tentacle-scale single. 



