72 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 9 



behind the anterior nostrils, forming a quadrangle. Upper h'p with five 

 pores on each side under its edge, about equally spaced, one before ante- 

 rior nostril, two between anterior and posterior nostrils, one just behind 

 the posterior nostril and one at the angle of the jaws. Lower jaw with a 

 series of four pores on each side, the last about below the end of the gape. 



Maxillary teeth laterally in two rows (at one point two thirds of the 

 way back on jaw, in three irregular rows), the outer row of very small 

 teeth, the inner row of somewhat larger ones. Maxillary teeth separated 

 anteriorly from the large, circular patch of premaxillary teeth, which are 

 scarcely separated from those on the shaft of the vomer. The vomerine 

 teeth begin with one median tooth and extend backward as two regular, 

 rather widely separated series, which gradually run close together and 

 finally coalesce into a single series posterior to a vertical from the end of 

 the orbit. Mandibular teeth on each side anteriorly in a wide band of 

 three or four rows, the bands of the two sides appressed anteriorly ; pos- 

 teriorly the band narrows to a single irregular series ; anteriorly the inner 

 teeth are largest. All teeth in mouth pointed, those of the premaxillary 

 and vomer stouter and larger than the others. 



Dorsal and anal fins high, confluent around end of tail. Origin of 

 dorsal over gill openings. No pectoral fins. 



Body longitudinally bicolor to a point about a head-length behind 

 anus, the brownish dorsum sharply differentiated from the whitish under- 

 side. Posteriorly, on the tail, the light venter disappears and the color is a 

 uniform brown, slightly lighter below. At the origin of the dorsal fin the 

 light ventral color crosses the dorsum to form a collarlike band, and 

 another such band crosses the head in the occipital region. On the sides 

 of the snout, just behind the anterior nostril, a small patch of the brown 

 color descends to the lower part of the snout. Tip of lower jaw with a 

 dark patch at each side. Dorsal and anal fins light. 



This species is allied to Beebe and Tee-Van's apterus, which was 

 described from near Cape San Lucas, and of which we have an example 

 from Gorgona Island, Colombia. In bicollaris the dorsal fin is inserted 

 over gill openings instead of almost a snout length posteriorly to them as 

 in apterus. The larger eye and the distinctively different color pattern 

 also serve to distinguish this new form. 



LEPTENCHELYS, new genus 



Genotype. — Leptenchelys vermiformis, new species 



Body elongate, cylindrical, vermiform, becoming slightly compressed 



