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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 41. 



short, its depth .6 diameter of eye; snout very long, 2,8 in head, 

 flat, fohaceous, pointed in profile, width in front of eyes nearly equal 

 to length, the sides parallel, knife-hke, the tip very tliin, flat, and 

 broadly rounded, a well-marked lateral angle occurring at the nostril, 

 a distinct median cartilaginous keel on upper and lower surfaces; 

 eye large, lateral, the length of orbital slit about equal to distance 

 from eye to lateral angle of snout and 1.75 times in interorbital 

 space, pupil about half way between last gill slit and end of snout; 

 mouth broad, moderately curved, its width equal to distance from 

 eye to first gill slit; a long, straight groove as long as eye at angle 

 of mouth, the groove inclined obliquely forward and inward, and if 

 produced meeting its fellow at a point opposite anterior third of 

 eye; preoral space long, more than .5 head; nostrils large, inferior, 

 oblique, extending to margin of snout at angle, width of each nostril 



Fig. 3.— Nasisqualus profundorum. Under side of head. Seven-eighths natural size. 



nearly one-third width of snout; teeth as indicated in generic descrip- 

 tion; spiracles large, about diameter of pupil and separated from eye 

 by a space greater than their diameter; skin velvety, densely scaled, 

 each denticle consisting of three slender spines in the form of a tri- 

 dent, the denticles deficient on margin of fuis. 



Dorsal fins nearly equal in length; origin of first dorsal midway 

 between second dorsal and anterior angle of orbit, length of base 

 (exclusive of spine) equal to distance between center of spiracles, the 

 spine one- third exposed and .6 height of fin; second dorsal fin liigher 

 than first, beginning behind base of ventrals, its base longer than 

 that of first dorsal, its posterior rays shghtly produced and nearly 

 reaching caudal fin, the spine long, .5 expose, .75 height of fin; caudal 

 fin, from anterior edge of lower lobe, equal to distance from snout to 

 first gill slit, lower lobe .5 total length, its distance behind ventral 

 base equal to .5 length of head; middle of ventral base midway from 



