MUSEUM OF COMPAEATIVE ZOOLOGY. 133 



the second and third moiith-papilla3 from corner of mouth-slit were flat and 

 blunt. 



Station 232, 340 fathoms, 6 specimens. 



OPHIOPYREN * gen. nov. 



Disk granulated. Teeth ; no tooth-papilla3 ; numerous mouth-papillas ar- 

 ranged in a close lin«. Mouth-frames long and conspicuous. Side mouth- 

 shields small t and widely separated by the mouth-shield. Under arm-plates 

 divided in two parts by a crease or joint. Arm-spines standing on outer edge 

 of side arm-plates. Two genital openings in each interbrachial space. 



Ophiopyren stands nearest Pectinura, from which it is distinguished by the 

 divided under arm-plates and the tendency to minute grain-like papilla) along 

 the genital opening. The peculiar division of the under arm-plates by a crease 

 or soldered joint rises in this way ; near the tip of the arm the inner piece of 

 the plate occupies most of the space, under form of a long narrow plate having 

 a sharp angle without, where are the tentacle-pores bordered by a narrow riui, 

 and this rim, growing gradually wider and thicker, forms the outer piece as it 

 appears near the base of the arm. 



' Ophiopyren brevispinus sp. nov. 



Plate VII. Figs. 173-175. 



Special Marks. — Three very short, blunt arm-spines. Mouth-shields longer 

 than broad, pentagonal. 



Description of an Individual (Station 173). — Diameter of disk 3.8 mm. 

 Width of arm without spines 1 mm. Thirteen or fourteen mouth-papilla3 to 

 each angle, of which the outer one on each side is much the largest, and the 

 rest are short and square, except the one at the apex, which is more pointed. 

 Mouth-shields longer than broad, pentagonal, with long pointed angle within ; 

 length to breadth .8 : .5. Side mouth-shields squarish and very short, widely 

 separated by inner angle of mouth-shield. First under arm-plate much broader 

 than long, of an irregular oval form ; second plate as long as broad, pentago- 

 nal, with a blunt angle inward ; third plate similar, but with a sharper angle 

 within ; those beyond grow proportionately longer, and become gradually 

 wedge-shape, with a truncated angle inward. Each plate is apparently divided 

 in two parts, the inner one more or less diamond-shaped, the outer made up of 

 the remainder of the plate. Upper arm-plates four-sided, somewhat wider 

 without than within, lateral sides straight, outer side slightly curved. Side 

 arm-plates not swollen, meeting neither above nor below. Disk flat and romid, 



* o(^ty, a snake ; wpriv, a kernel. 



t Their strict homology with the side arm-plates is very plain in this genus, 

 especially in 0. longispinus. 



