UPllIOGLYPIIA KOBUSTA. 45 



Ophioglypha robiista Lvm.vn. 



Op/iiolejjis rohiista Ayuics. rroccod. Boston Soc. Nat. Hist., IV. p. i;{4. 1851. 

 Opiiiuru fasciculala FoiUJES. Appendi.v to Suthcrlamr.s Journal ol' a Journey. 

 0/t/ihira squnmosa Lutkkn. Vidensk. Mcdilelcilser. Nov., 18o4. 

 Op/iiura sijuaiiiosa Lutken. Addit. ad llist. Oph., p. 4G. 



Special Marks. — Mouth-sliiekls nearly heart-shape, l)roa(ler than 

 long ; arms very finely tapering, as long as three or four times the 

 diameter of the disk. 



Description of a Specimen. — Diameter of disk, 7.7™'"' ; from outer 

 side of mouth-shield to outer corner of opposite mouth-slit, 3.8"""- ; 

 width of arm without spines, 1.2""" ; length of arm, o2'"'"- ; distance 

 from outer side of mouth-shield to inner points of mouth-papillae, to 

 that hetween outer corners of mouth-slits, 2 : 1.8. Mouth-papilkv, seven 

 or eight to each angle of mouth ; outermost one broadest, thin, flat, 

 squarish, with a bevelled cutting edge ; three innermost ones forming a 

 row at the inner mouth-angle ; nearly equal, stout, rounded, pointed ; 

 all pointing to centre of mouth. Teeth, five or six, equal, crowded, 

 sh;u'}), Ihit, Avith curved sides, like a spear-head. Mouth-shields broad 

 heart-shape, strongly curved without, within pointed, broader than long, 

 length to breadth, 1.2 : 1.5. Side mouth-shields occupying inner sides 

 of mouth-shields, meeting within ; long, narrow, but little brotider with- 

 out than within. Under arm-plates broader than long, bounded without 

 by a slightly re-entering curve ; on the lateral side, by a very short, 

 nearly straight line ; and within by two re-entering curves, converging 

 in a peak ; length to breadth (sixth plate), .5 : .7. First plate quite 

 different from the others, being nearl}^ oval ; length to breadth, .5 : .8 ; 

 second plate proportionately longer than those beyond ; at tip of arm, 

 l^ltites heartrshape, and extremely minute, compared with size of joint. 

 Side arm-plates strongly developed, meeting below, and there forming 

 a line of juncture, which, at base of arm, is al^out half as long as an 

 under arm-i)late ; not meeting above till nearly half-way out on arm. 

 Upper arm-plates diamond-shape, with outer angle rounded, and inner 

 angle truncated, sometimes approaching a hexagonal shape ; length to 

 breadth (fifth plate), .7 : .9 ; first two or three plates rudimentary and 

 irregular, of these usually two are embraced in the notch of the disk ; 

 near end of arm, plate heart-shape, with a sharp point inward. Disk 

 scales irregular in shape and size, none very large, very little swelled ; 

 ]U"imarv plates not prominent ; near margin of disk about 4 to a square 

 mm. ; the largest scales have a diameter of .8"""- ; below, scales veiy 

 similar, but not quite so large. Eadial shields inconspicuous, irregularly 

 triangular, aljout as long as broad, somewhat overlapped by neighboring 



