3G2 DEEP SEA FISHES. 



placed so as to bring tlieir functional field most completely within the field 

 of vision, a fact which sti'ongly supports the theory of luminous disks on 

 certain species. Those disl^s out of the visual field, or better those function- 

 inc toward points not reached at the same instant by the eye are less devel- 

 oped. Thus it happens that the disks on the forward portion of the snout 

 and those back of the head at the angle of the gill opening are smaller thnn 

 tliose nearer the eye, while, being in better position, they are larger than 

 those below the lower jaws. Similar statements may be made concerning 

 the species of Eretmichthys. On the head of B. nasus there are 58 disks. 



Eretiiticldhys piunattis and E. occUa, Plate LXXIX., resemble Bafisoschis 

 iiasns in regard to differences in tlie developement of the disks on different 

 parts of the head ; neither of them has frontal branches and each has two 

 disks in each aural branch. These forms are readily separated by details 

 of the system, though the pectoral oars of E. jjiimatus and the pores on the 

 head of E. ocella render it hardly necessary to go below the sui'face for aid. 

 E. pinnalus has 54 cephalic disks and E. ocella has 56. 



Bassogigas skiliferoides and Caiivti/x siimis, Plate LXXX., belong to very 

 distinct /genera. The most prominent differences in the sj'stems, besides 

 that in the number of disks, are perhaps those due to the elongation and 

 the depress:on of the head in Cata^tyx : the disks are far apart in the 

 longitudinal canals and close together in the vertical, that is, in the post- 

 orbital and the spiracular. In both species the disks are comparatively 

 small and are of nearly uniform size on all parts of the head ; both are 

 without frontal branches. B . stelliferoidcs has 64 cephalic disks, tw^o of them 

 in each aural branch, and C simus has 50 disks on the head, but one of 

 which appears in each aural. 



Lamprogramnms illustris and Ph//ds regius, Plate LXXXI., present differ- 

 ences of the most marked character. The disks of the first are large but 

 very slender aud spindle-shaped ; the series are complete ; and, a feature 

 not yet noted on others, the frontal branches have joined the aurals forming 

 a, complete loop, which, however, contains but three disks, the one ordi- 

 narily found in each frontal branch and the two most often occurring in each 

 aural. There are 56 cephalic disks ; those of the body are similar to those 

 of the head. On Phycis regms the disks about the eyes are the better 

 developed ; those on the aural region are rudimentary and obsolescent, 

 their places being occupied by a cavity of some size, filled with a gelatinous 

 mass and mucus, into which canals are carried as hard-walled tubes, one 



