Fishes of the Western North Atlantic 355 



distance a little greater than that from its own origin to cloaca, then narrowing to a 

 low ridge that merges gradually with general contour of tail; maximum breadth of 

 lower tailfold (under middle of spine or spines) about ^3 as great as height of tail 

 at same point. 



Tail spines one, sometimes two or three, with replacement spine growing anterior 

 to older ones on specimens studied ;*5 distance from origin of first spine to center of 

 cloaca about 47-60 "/o as long as distance from cloaca to snout; length of free portion 

 of fully formed spine about half as great, its total length from origin about 70 "/o as 

 great, as distance between outer margins of orbits; maximum breadth of spine about 

 7—8 "/o of its total length; about 40 teeth along distal two-thirds of spine on each 

 side of spine of specimen counted. 



Skin, apart from tail spines, wholly smooth on specimens up to 18—19 inches 

 broad; thereafter a median series of tubercles or bucklers with blunt-tipped conical 

 thorn developing from nuchal region to tail spine ;^* some of these bucklers large, 

 others small, arranged either in a single row or in two or three irregular rows, depending 

 on whether one, two or three thorns are borne on a single basal plate; bucklers on disc 

 with longitudinally oval bases mostly imbedded in skin and without noticeable striae, 

 but bases of those on tail oval to round and conspicuously striate; shoulder region on 

 either side of median line of half-grown specimens and larger armed with 1—20 larger 

 bucklers,®' either single or with two or three springing from a single base, irregularly 

 distributed, often with many more on one shoulder than on the other; one buckler also 

 close in front of each eye; a few large and conspicuous single or multiple tubercles, 

 on bases sometimes up to 25 mm in diameter, likewise finally develop on the outer 

 posterior part of either side of the disc®* of medium-sized specimens and larger; their 

 discs also sparsely and irregularly strewn with prickles of various sizes. Upper surface 

 of posterior part of tail from spine to tip, and sides of tail from about abreast the mid- 

 point of its lower fold, rough with conspicuous thorns, decreasing in size rearward. 

 Lower surface of disc smooth ; lower surface of tail thorny rearward from about below 

 tip of spine. 



Snout in front of orbits about 0.9—1.2 times as long as distance between outer 

 edges of orbits, its length in front of mouth about 1.6-1.8 times as great as distance 

 between exposed nostrils and 0.9—1.0 times as great as distance between inner ends 

 of first gill openings. Orbit about 59—67 "/o as long as distance between orbits and 

 0.9—1.0 times as long as spiracle. Distance between inner ends of first gills about 1.8- 

 2.0 times as long as distance between exposed nostrils; distance between inner ends 

 of fifth gills about 70—75 "/o as long as that between first gills. Nasal curtain reaching 

 about to front of mouth, its free posterior margin nearly straight or weakly concave 



65. As identified by their relative states of development. 



66. A female specimen 35 inches wide from Buzzards Bay has a midrow of spines from nuchal region to tail, but one 

 of the same size, a male, from Cape Hatteras, lacks these spines anterior to the axils of pectorals except for a single 

 one at the highest part of the back. 



67. Their bases sometimes up to 25 mm in diameter. 



68. On a male 41 inches wide there are two of these and one small thorn on the right-hand side, three on the left, but 

 a somewhat larger number on a female of 60 inches. 



23* 



