530 Memoir Sears Foundation for Marine Research 



Upper anterior (vomerine) dental plates subtriangular, their outer anterior out- 

 lines convex, with 6-8 rodial ridges, the number increasing with growth." Posterior 

 upper (palatine) plates about 2.7 times as long as anterior plates, irregularly rhomboid, 

 about twice as broad posteriorly as anteriorly; outer margin rounded with wear, without 

 distinct radial ridges, but posterior surface with one large rounded prominence (tritor), 

 its anterior outline somewhat indented. Lower (mandibular) plates about as long as 

 posterior upper plates, of shape illustrated in Fig. 120, the edges more or less rounded. 



Figure 119. Chimaera aibana. A Side view of head of same specimen as in Fig. 118, to show mucous canals. 

 B Ventral view of head of same. C Ventral view of clasper of same, about 0.7 X. D Posterior part of dorsal fin, 

 origin of caudal fin, and anal fin of female 690 mm long to upper origin of caudal fin, from off Matanzas, Cuba 

 (Harv. Mus. Comp. Zool., No. 34728), about 0.5 x. 



with about 12 radial ridges on larger specimen -,5* the central part with one large 

 rounded swelling (tritor). 



Dorsal spine about as long as distance from tip of snout to origin of pectoral, its 

 tip reaching a little beyond apex of first dorsal fin; Its outer half free from fin, the rear 

 surface with a longitudinal groove edged on each side with a series of 55-60 small 

 sharp thorns pointing toward base and decreasing in size toward tip. First dorsal fin 

 with narrowly pointed apex and moderately concave posterior margin, its base (origin 

 of spine to bottom of interdorsal notch) about as long as its vertical height along an- 

 terior margin. Second dorsal separated from first by a low fold of skin without horny 

 rays. Second dorsal with upper margin nearly straight, its height about as great at 



55. Six ridges on specimen pictured (Fig. 120); apparently 8 or 9 on our largest specimen, but so worn down that an 

 exact count cannot be made. 



56. Too much worn down for accurate counting. 



