150 THE PLAGIOSTOMIA. 



Hemigaleus pectoralis. 



Plate 4, fig. 1-5; Plate 50, fig. 9, (eye); Plate 52, fig. 2, (pelvis); Plate 58, fig. 4. 



(intestine). 



Hemigaleus pectoralis Gabman, 1906, Bull. M . C. Z., 46, p. 203. 



Outlines in general, positions, and shapes of fins, etc., resembling those of 

 Galeorhinus mustdus or Eugaleus galeus. Head less than one fourth of the total 

 length, little less than half the body cavity, depressed, broader than higli; snout 

 depressed, blunt edged at the sides, broadly rounded from the nostrils forward, 

 blunt at the end. Nostrils midway in the preoral length, large, with a fold on 

 the middle of the front edge from which springs the prominent rounded lobe of 

 the \'alve, hinder valve a narrow ridge around the eductal section of the nostril. 

 Eye medium, pupil elliptical, horizontal, orbit about one third of the preoral 

 length of the snout. Mouth wide moderately arched, width three fourths of the 

 distance from the end of the snout; labial folds half as long as the jaw on each 

 side, hinder shorter. Teeth in 11 rows, varied in shapes and sizes, Plate 4, fig. 

 2-3 ; upper oblique, notched, or deeply excavated on the outer edge and denticu- 

 late on the basal portion (median 5 or 6 rows with less distinct denticles on the 

 inner edge also), median two or three rows of smaller more erect teeth; lower 

 teeth with erect narrow cusps on broad bases, without denticles. Anteriorly 

 on the upper jaws there are several series of teeth in function, laterally there is 

 but a single series; the small teeth of the symphyseal rows are about erect and 

 each has one or more denticles on each edge. Spiracle larger than the pores, 

 directly behind the eye and distant from it half the length of the orbit. Length 

 of orbit more than greatest width of gill openings. Pectorals falciform, three 

 fifths as wide as long, when applied to the side subtending six sevenths of the 

 base of the dorsal, hinder margin concave, inner angle rounded. Dorsals alike 

 in shape, hinder angle long pointed, upper blunted; space between dorsals less 

 than length of caudal. Ventrals as large as the second dorsal, below the middle 

 of the space between the dorsals. Anal half as large as the second dorsal, origin 

 httle farther back, end of base little behind the end of the base of that fin. Cau- 

 dal moderate, length about one fourth of the total, pointed, a deep notch behind 

 the subcaudal fin, subcaudal lobe sharp. Scales small, pedicellate, five-keeled, 

 each keel ending in a point ; inside of mouth and throat covered by sharp scales. 



Greyish brown, olive in life; fins dark with light hinder margins; lower 

 surfaces fighter. 



