176 DEEP SEA FISHES. 



Over tlio head the mucous and luminous sj^stems are pecuharly dis- 

 tributed. In some measure their arrangement recalls that seen in the 

 cephalic canals of the lateral system on certain Selachia ("On the Lateral 

 Canal System of the Selachia and Ilolocephala," 1888, and Plate LXX., 

 below). While the structures in these cases are very different the resem- 

 blances in locations are sufficiently close to permit the iise of similar terms 

 in description. The cephalic canals are tortuous and the fusiform disks, 

 being transverse, are not as on the body vertical to the general axis, but 

 are directed toward all points. On the top of the head two rostral series 

 converge backward from the foremost of the glandular spindles until near 

 the interorbital space where they become divergent and, as cranials, traverse 

 the space to the frontal region behind it, on reaching which each branches 

 to send one branch inward nearer the median line of the crown and another 

 out to pass backward nearer its edge. At the back of the skull each of the 

 inner branches turns outward and passing down and backward reaches the 

 hindmost organ of the cephalic series on the post-temporal (scapula). In 

 each of the cranial series there are eleven of the glandular bodies. From 

 the outer branch of each cranial the orbital and the suborbital series, of 

 seven glands, passes down behind the eye and^forward below it. Farther 

 back from the end of the outer cranial branch there is a short occipital 

 thread without spindles connecting the outer with the inner branch, and an 

 opercular series extends down on the preopercle and then continues forward, 

 as the oral, imder the lower jaw- No aural connection was to be traced. 

 Between the cranial and the mandibular symphj'sis there are nine of the 

 huniuous disks. On each side of the head there are twenty-five of the 

 glandular spindles, which with the forty on each side of the body make one 

 hundred and thirty in all. It is difficult from the material at hand to deter- 

 mine the connection between the series on the head and those on the body ; 

 the thread connecting one gland with another disappears on the post-temporal 

 and reappears again at the first spindle on the body. Whether the thread 

 is continuous, as is to be expected, is still problematical. Innnediately be- 

 hind the head the thin scale-covered black skin extends down along the 

 shoulder girdle to the abdomen. Beneath tliis skin above the pectoral the 

 large .scales appear to be isolated and each to lie at the bottom of a sac 

 surrounded by membranes that are attached at the edges or between the 

 scales. Bits of what may have been coagulated mucus occur in some of the 

 sacs; unless they have been greatly macerated the structures are hardly 

 like those of the disks in the lateral line. 



