674 GREENE. [Vol. XV. 



to in front of the opercular spine, where it sinks into a canal. 

 This canal extends along the posterior border of the preopercle, 

 around the angle of the mouth, and forward on the ventral sur- 

 face of the mandible to near its anterior end, where the line 

 comes again to the surface and ends at the symphysis of the 

 jaw (PL XXXVIII, Fig. 2). There are eight pores or openings 

 to the canal portion. This line contains twenty-one organs, 

 seven at the upper free end, seven in the canal, and seven at 

 the lower free end. At the upper free end there are occa- 

 sionally rudimentary phosphorescent organs between the sense 

 organs — an average of one. 



There are two "opercular" rows, an upper and a lower. 

 The upper row, u op, contains ten phosphorescent organs and 

 fourteen sense organs. These are arranged in parallel lines, 

 the phosphorescent organs above and the sense organs immedi- 

 ately below them. The line begins posterior to the second 

 pore from above of the operculo-mandibular canal, and extends 

 in a curve backward and upward, over the operculum, to a point 

 posterior to the opercular spine. The row of sense organs is 

 the longer of the two. 



The lower row, I op, contains from two to ten phosphorescent 

 organs, on an average four, and an average of seventeen sense 

 organs, the phosphorescent organs occurring between the sense 

 organs at the base of the line. The row begins opposite the 

 third operculo-mandibular pore and extends backward and up- 

 ward to near the posterior angle of the opercular flap. The 

 curvature of the lower row is a little greater than that of the 

 upper, the two ending near each other. 



The infraorbital consists of two portions, a preorbital and a 

 suborbital, each of sense organs. The preorbital or nasal 

 portion is made up of a row of four to six organs from the 

 posterior nasal opening to the base of the anterior nasal papilla, 

 two pairs of organs between the anterior nasal papillae, and two 

 to three more in a transverse line at the posterior base of the 

 tube. The suborbital extends from the posterior nasal open- 

 ing around under the eye to the anterior pore of the temporal 

 canal. It contains fourteen sense organs and one large phos- 

 phorescent organ below the posterior border of the eye. 



