LOPHIUS PISCATOEIUS. 17 



violet-gray color ; but, owing to the great development of black pigment in 

 the embrvo, the band has a somewhat blackish appearance. The eggs are 

 arranged in a single irregular layer, and each is enclosed in a gelatinous 

 envelope which has about twice the diameter of the egg, and which thus 

 gives space enough for it to move freely. The envelopes are thin and 

 membrane-like, and glued together by a homogeneous layer of mucous 

 (Figs. 1 and 2). Pressure causes the envelope to wrinkle, showing that it is 

 really membranous in character, although it may be only a modified layer of 

 the mucous mass. 



The egg is very large, measuring 1.75 mm. in diameter, and has a single 

 immense oil-globule (.40 to .42 nun. in diameter) of a beautiful transparent 

 copper-color (Fig. 1). The yolk is transparent, like that of all the pelagic 

 fish eggs we have described. In the youngest stage which we have obtained 

 (Fig. 1) there is already a dense veil of black dendritic cells on the ventral 

 side of the embryo, which obscures its outlines. The pigment extends over 

 the dorsal surface also, so that the embryo appears to the naked eye as a 

 black streak across the egg. The pigment increases rapidly, and a little 

 later we find the eyes perfectly black (Fig. 4) and the oil-globule enveloped 

 in a thick network of these cells. The pigment spreads to other parts of 

 the yolk, but is mainly concentrated on the dorsal side beneath the embryo. 

 Fig. 9 gives a good idea of the appearance of the pigment shortly before 

 hatching. 



At the time of hatching, the yolk-sac is quite globular, but much 

 reduced in size. In this stage the young fish bears little resemblance to 

 the adult form. It has only a single (first) dorsal appendage, a narrow, 

 short spatulate ventral, and a small circular pectoral. (See Agassi/., he. tit., 

 PI. XVI. Fig. 4.) In this stage, as well as while still in the egg, and until 

 it is far more advanced, the embryo is remarkable for the great width of 

 the embryonic fold, the straight notochord. and the three or four prominent 

 patches of intense black pigment placed at equal intervals along the lower, 

 upper, and terminal parts of the chorda. The tail pigment-spots extend on 

 both sides of the chorda, and form the largest of the three patches. This 

 is the case from the earliest stages, until the body of the young Lophius 

 is completely covered with pigment. In the earlier stages the embryonic 

 fold is covered with minute, round black pigment-spots. It is only m 

 much more advanced stages that we begin to find traces of the ordinary 

 dendritic spots which eventually cover the dorsal, anal, and caudal fins. 



