 The two dorsal fins are placed far back on the body ; the first is larger than the second and originates over the bases of the pelvic fins . The pectoral fins are large . In males , the inner margins of the pelvic fins are merged into an " apron " over the claspers . The caudal fin is broad and nearly horizontal , with an indistinct lower lobe . The skin is very rough , due to a covering of large , upright dermal denticles . The nursehound has small black dots covering its back and sides , interspersed with brown spots of varying shapes larger than the pupil , on a grayish or brownish background . The pattern is highly variable across individuals and ages ; there may also be white spots , or the brown spots may be expanded so that almost the whole body is dark , or a series of faint " saddles " may be present . The underside is plain white . 
