MUSEUM OF COMPARATIVE ZOOLOGY. 109 
Ophiomusium serratum sp. nov. 
Plate I. Figs. 23, 24, 25. 
Special Marks.— Arms rather slender and tapering, cylindrical or but 
slightly wavy. Upper and under arm-plates persisting nearly to end of arm, 
but no tentacles beyond third or fourth under plate. Genital opening bounded 
by small close-set papilla. Interbrachial space between radial shields occu- 
pied by two large plates. Papillw along genital openings extending upward 
as a small arm-comb. Four or five small arm-spines. 
Description of an Individual (Station 23). — Diameter of disk 10 mm. 
Width of arm near disk, without spines, 2.5 mm. Mouth-papille six on each 
side, with one at angle of jaw, all in close contact. Mouth-shields heart or 
rounded-diamond shape, with an angle inward ; length to breadth 1.5 : 1. 
Side mouth-shields long triangular, extending farther out than the mouth- 
shield ; wider without than within, where they just meet. The first four 
under arm-plates bearing tentacle-scales are pentagonal, with au obtuse angle 
inward, outer edge slightly curved, lateral sides re-enteringly curved ; length 
to breadth, second arm-plate, 1. : .7. Side arm-plates thick, constricted 
within, meeting below, even within the disk, and above beyond the second 
upper arm.plate ; those beyond are also pentagonal, but small, broad, and 
widely separated. Upper arm-plates triangular, with an acute angle inward, 
and outer edge curved; length to breadth 1 :.7. Disk covered with flat 
plates closely soldered ; in the central space within the radial shields are six 
rounded primary plates, separated by a circular row of small ones ; the inter- 
brachial space is occupied by two angular plates, the outer one much larger. 
Radial shields long triangular, separated their entire length by one small and 
two large scales. In the interbrachial space below are two large circular 
plates, extending from the mouth-shield to margin of disk, on either side of 
which are smaller circular scales. Genital scales long and very narrow, ex- 
tending from the edge of the mouth-shield to margin of disk, on the free edge 
of which are fine tooth-like papilla, corresponding to similar papilla along the 
side mouth-shields, giving a resemblance to Ophioglypha. At the base of the arm 
above are short blunt papille on either side of first upper arm-plate. Arm- 
spines four or five, delicate, pointed, nearly equally placed ; middle one longest 
and nearly half as long as a side arm-plate. A single circular tentacle-scale 
on second, third, and fourth under arm-plates, situated near the inner angle. 
The entire surface of the animal is microscopically tuberculated. Color in 
alcohol, white. 
Station 23, 450 fathoms, 1 specimen. 
Ophiomusium armigerum sp. nov. 
Plate I. Figs. 21, 22, 
Special Marks. — Arms rather slender and tapering, cylindrical or but 
slightly wavy. Upper and under arm-plates persisting nearly to end of arm, 
