ACANTHIDIUM ACICULATUM. 217 



ACANTHIDIUM ACICULATUM. 



Plate 12, fig. 1-1. 

 Acanlhidium aciculatum Gahman, 1906, Bull. M. C. Z., 46, p. 207. 



Elongate, moderately slender and compressed. Head long, nearly one 

 fourth of the total length; snout produced, depressed, sharp laterally, broad and 

 bluntly rounded at the end superiorly. Nostrils small, their distance apart 

 about two thirds of their distance from the end of the snout, which latter distance 

 is one third of that from the end to the mouth; anterior valve with a short 

 pointed lobe crossing the nostril. Eye large, three sevenths of the length of the 

 snout, hind angle of the orbit above the angle of the mouth. Mouth wide, 

 width nearly half the length of the snout, moderately arched, with a deep groove, 

 more than half of which is anterior, and with labial folds, at each angle; lower fold 

 more than half the length of the jaw, upper shorter and hidden by the groove. 

 Teeth §?; upper with sharp erect triangular cusps rising from the middle of the 

 cutting edges, broadening at the bases, little more oblique near the angles; lower 

 with a group of erect, sharp-pointed teeth near the symphysis, somewhat like 

 those on the upper jaws of A. hystricosum, and becoming slightly oblique toward 

 the corners of the mouth; base of cusp much broader than the central portion, 

 Plate 12, fig. 2. Spiracle large, distant less than a diameter from the corner of 

 the eye, valve with laminae like the gills. Gill openings narrow, subequal, about 

 one third of the length of the orbit, in front of the pectoral. Pectorals sub- 

 quadrate, subtruncate, five eighths as wide as long, not reaching a vertical from 

 the dorsal spine by more than the width of the pectoral fin, angles rounded, inner 

 shorter. First dorsal spine remote from the end of the pectoral, lower than the fin, 

 not half exposed ; upper margin of fin in a low cont inuous curve from the spine to 

 the much produced extremity; two fifths of the base of the fin in the hinder half 

 of the length from end of snout to caudal. Second dorsal much higher than the 

 first, base one fifth shorter; spine nearly as high as the fin, little behind the axils 

 of the ventrals, half or more exposed; acute free portion of the fin nearly reaching 

 the origin of the supracaudal. Ventrals small, ends hardly reaching the middle 

 of the base of the second dorsal without the spine, bases distant from the origin 

 of the caudal one third of the distance from the axils of the pectorals. Sub- 

 caudal angle broadly rounded; terminal margin convex; caudal less than one 

 fourth of the total length. Scales very small, slender, pedunculate, each with 

 three slender sharp cusps. 



