554 Memoir Sears Foundation for Marine Research 



Snout narrow-triangular, more or less flattened above and below, wider transversely 

 than vertically, its lateral margins converging to slender tip; soft on small specimens, 

 stiff on larger, especially toward tip ; movable in the vertical plane at base and also about 

 V5 of distance out along its length where unpaired rostral cartilage is flexible (p. 519); 

 curving upward slightly in large females, abruptly so along anterior Vs— V4 i^^ mature 

 males; tip smooth in females, but with a double series of low and hard rounded knobs 

 at maturity in males, their arrangement as shown in Fig. 125. Eye about V3 of vertical 

 height of head at center of eye; its length about 1/7 of length of head from snout to origin 

 of pectorals. Gill openings about half as long as eye; distance across throat between 

 inner ends of gill openings about as long as eye, marked by an indistinct furrow. 

 Exposed division of nostril oval, a little longer than broad, about 8-10 "/o as long as 

 eye; distance from its rear edge to rear edge of upper lip about twice as great as its 

 own length. Width of mouth, when closed, about ^/g as great as length of eye. Tongue 

 with a few fleshy swellings and many smaller papillae of various sizes. 



Dental plates smooth at hatching, a series of grinding surfaces developing soon 

 thereafter. Upper anterior (vomerine) plates cupped from front to rear, their outer 

 anterior margins nearly straight or weakly convex with 7-9 rounded knobs or short 

 radial ridges that may be entirely obliterated by maturity in some specimens;"' inner 

 margins smooth or with 2 or 3 low knobs. Posterior upper (palatine) plates about 2.5 

 times as long as anterior plates, subtriangular, about twice as long as broad; anterior 

 part and outer margin with variable numbers of small rounded knobs of various sizes; 

 inner posterior part with a single large swelling foreshadowed on some small specimens 

 by a series of about eight transverse ridges. i"* Lower (mandibular) plates about as long 

 as palatine plates, the free edges more or less irregular, probably depending on wear; 

 anterior and outer margins with irregular (single or double) series of small rounded 

 knobs that persist to maturity on some specimens but may be partially reduced to in- 

 distinct radial ridges on others even at an early stage in growth;!"' ^Iso a more or less 

 prominent medial longitudinal ridge foreshadowed on at least some small specimens by 

 a series of transverse ridges. 



Dorsal spine about over gill openings, about half as long as distance from tip of 

 snout to rear edge of eye, reaching a little beyond apex of first dorsal fin ; its outer V2-V3 

 free from fin, compressed laterally, with rear face somewhat channelled longitudinally 

 and having two rows of serrations of characteristic form (Fig. 124E). First dorsal fin 

 triangular with acute apex, its posterior margin nearly straight; base (origin to midpoint 

 of interdorsal notch) about */5 as long as anterior margin. First and second dorsal fins 

 connected at bottom of notch by a low fold of skin, without definite interspace. Second 

 dorsal rising gradually to maximum height a little anterior to level of tips of pectorals 



107. The margins of the upper anterior plates have these knobs on one mature male examined by us, but they are 

 pictured as entirely smooth for a large female (Roule and Angel, Result. Camp. sci. Monaco, 86, 1933: pi- 4, 

 fig. 34c). 



108. So pictured by Garman (Bull. Mus. comp. Zool. Harv., 41, 1904: pi. 5, fig. 4). 



109. Marginal knobs are well developed on a mature male that we have seen and on a large female also (Roule and 

 Angel, Result. Camp. sci. Monaco, 86, 1933: pi. 4, fig. 34d), but they show only faintly on a smaller male 

 (Fig. 123). 



