Fishes of the IVestern North Atlantic 245 



By maturity the thorns decrease in number on the shoulder regions, around the 

 eyes, and on the rostral ridge and the bare areas expand over most of the inner parts of 

 the pectorals, but mature females develop large thorns, widely spread, over the posterior 

 corners of the pectorals, the thorny areas expanding over the posterior lobes of their 

 pelvics; a few thorns also appear on the anterior lobes. Mature males develop 4—6 ir- 

 regular rows of conspicuous thorns over a narrow triangular area from the tips of the 

 pectoral cartilages back about to the level of the eyes. Alar spines of mature males are 

 ordinarily in three rows, these appearing when the claspers extend about a third of the 

 way back from the tips of the pelvics toward the end of the tail; 19—2 i spines in each 

 of the two inner rows, 10—12 in the outermost. The lower surface is smooth in small 

 specimens, but the tip of the snout becomes prickly with growth, as does a narrow band 

 along the anterior margins reaching rearward to the level of the mouth in half-grown 

 specimens and for some distance posterior to the mouth in adults. 



Snout in front of orbits about 2.0—2.3 times as long as distance between orbits; 

 its length in front of mouth 1.4-1.7 times as great as distance between exposed nostrils. 

 Orbit about 65—70 "/„ as long as distance between orbits, and i. 0—1.2 times as long as 

 spiracle. Distance between first gill openings 2.1—2.5 times as long as distance between 

 exposed nostrils, between fifth gill openings i. 0—1.3 times; first gill openings i. 0—1.2 

 times as long as fifth and about 18—22 "/q as long as breadth of mouth. Nasal curtain 

 fringed, expanded posterior (outer) margin of nostril with very short fringe, sometimes 

 irregular and easily overlooked. Mouth but little arched, hardly more so in males than 

 in females." 



Teeth yfZn^; those of young and of females to maturity rounded, or sometimes 

 with blunt cusp faintly indicated, and close-set in quincunx; those of mature males with 

 high conical cusp blunted at tip, more widely spaced in transverse series.'* 



First and second dorsals similar in size and shape, the two confluent at base. Caudal 

 membrane posterior to second dorsal about Vi—Vs ^^ '°"§ ^® h'i.^^ of first dorsal. Pelvics 

 moderately concave outwardly, weakly scalloped around the indentation ; anterior margin 

 about 59-66 o/o as long as distance from its own origin to rear tip of pelvic; anterior 

 lobe broad, including 4-5 radial cartilages besides the first and stoutest; posterior lobe 

 weakly convex outwardly, its rear corner narrowly rounded. Claspers of sexually mature 

 males extend about halfway from axils of pelvics toward tip of tail. 



Anterior rays of pectorals extending forward about 80 to 90 "/o of distance from 

 level of fronts of orbits toward tip of snout in most specimens, reaching almost opposite 

 tip of snout in others. 



Color. Light brown above, with varying numbers of rounded blackish spots; on 

 half-grown specimens and larger, the spots usually about 3-6 mm in diameter and scat- 

 tered 8-12 mm apart on disc, pelvics, tail, and claspers of mature males; also, outer 



77. In R. erinacea at maturity the lower jaw is considerably more arched in males than in females. 



7S. In maturing males the replacement of rounded teeth by conical ones takes place when the claspers are about half- 

 grown; in a specimen of about Soo mm the lower rows of teeth are still of the immature shape, whereas in the 

 upper jaw the teeth in successive rows are progressively more and more conical from front to rear; i. e., from the 

 older rows of teeth to those more recently formed. 



