MUSEUM OF COMPARATIVE ZOOLOGY. 231 



angle, and on the sides by a re-entering curve. Side arm-plates occupying 

 about two thirds of the height of the arm, and having a cleanly curved outer 

 side. Upper arm-plates arched (but not so strongly as in O. hews), wider with- 

 out than within, and having straight outer and inner sides. Disk angular, 

 closely and evenly covered above, except the radial shields, with a fine granu- 

 lation having about six grains in the length of 1 mm. Interbrachial spaces 

 below have a reticulated look, from the numerous bare plates among the gran- 

 ulation. Radial shields wide oval ; length to breadth, 2.3 : 1.8. Genital open- 

 ing long, extending from mouth-shield nearly to edge of disk. Four or five 

 small, peg-like, even, spaced arm-spines, a little more than haK the length of a 

 joint. One stout, round tentacle-scale. 



Station 130, near Frederickstadt, 451 fathoms, 1 specimen. 



This species is well distinguished from P. heros and P. lacertosa by a flatter 

 arm, four or fi\'e peg-like spaced arm-spines, and naked plates in the lower 

 interbrachial space. 



Pectinura lacertosa sp. nov. 



Plate III. Figs. 4-6. 



Special iUarZ;s. ^ Three arm-spines about as long as a joint and standing 

 low down on side of arm. Indentations, but no pores, between the first four 

 or five lower arm-plates. Arms short ; only three and a half or four times the 

 diameter of the disk. One large, round tentacle-scale. 



Description of an Individual (Station 258). — Diameter of disk 35 mm. 

 Length of arm about 135 mm. Width of arm close to disk, without spines, 

 6 mm. About twenty mouth-papillge to each angle, whereof the two or three 

 outer ones are wide and squarish, while those within are sharp and peg-like. 

 The two lowest teeth are replaced by similar papillae. Mouth-shields short 

 heart-shape with a rounded angle within ; length to breadth, 4 : 5. There are 

 sometimes one or more large scales, or supplementary pieces, just outside. 

 Side mouth-shields very small and nearly obliterated. Under arm-plates 

 about as wide as long, bounded without by a curve, within by a truncated 

 angle, and on the sides by a re-entering curve. Side arm-plates low, occupy- 

 ing only about one half the height of the arm, and meeting neither above nor 

 below. Upper arm-plates highly arched, closely overlapping, with outer and 

 inner edges nearly straight ; each is usually broken in two pieces. Disk an- 

 gular, closely and evenly covered with very fine granules, 7 or 8 in the 

 length of 1 mm., except the radial shields and sometimes a small plate on the 

 margin. Radial shields egg-shaped, somewhat longer than broad with outer 

 and inner ends much roundeil ; length to breadth, 4 : 2.5. Lower interbrachial 

 space covered by a similar granulation, extending eiven to the mouth-angle. 

 There are none on the mouth-shields, outside wliich are one or more thick, 

 partially naked scales, representing the supplementary shield. Genital open- 

 ing long, extending from mouth-shield nearly to margin of disk. Three, some- 



