MUSEUM OF COMPARATIVE ZOOLOGY, 133 
the second and third mouth-papille from corner of mouth-slit were flat and 
blunt. 
Station 232, 340 fathoms, 6 specimens, 
OPHIOPYREN * gen. nov. 
Disk granulated, Teeth; no tooth-papille ; numerous mouth-papille ar- 
ranged in a close line. Mouth-frames long and conspicuous, Side mouth- 
shields smallt 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 papille 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 along narrow plate having 
a sharp angle without, where are the tentacle-pores bordered by a narrow rim, 
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 VIL. 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-papille 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 irtegular 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 round, 
* ¿pus, a snake ; muphv, a kernel, 
+ Their strict homology with the side arm-plates is very plain in this genus, 
especially in O. longispinus. 
