IN PORICHTHYS. 49 



cup-shaped, holding in the depression the rather thick con- 

 nective tissue capsule, on which rests the lens. The por- 

 tion of the capsule above the lens is thin. The fibrous 

 connective tissue above the lens is rather thick and firm. 

 No pigment is under the centre of the organ, but in the 

 tissue at the sides, and below the edges of the spicular 

 layer, there are a few flakes of it. The spicular layer thins 

 out at the ends, but some few spicules continue to the ad- 

 jacent organs. At the ventral or inner (nearest the fin) 

 side of the anterior end of the organ, a small blood vessel 

 goes over the edge of the spicular layer to the capsule, 

 from a blood-vessel at that side of, and below, the organ. 



Looking at the frontal organs (fig. S)in situ, the spicu- 

 lar layer reflects the light so as to give them the appear- 

 ance of minute silver dots. The spicular layer is thin, and 

 turned up at the inner (dorsal) side. Above, and lying on 

 the spicular layer, is a mass that corresponds, probably, to 

 the capsule of the outer anal, etc. Embedded in the cen- 

 tre of this mass is a smaller one of about the same shape, 

 which resembles the lens in staining darker than its ma- 

 trix. No distinct cells can be seen in any part of the mass, 

 nor is there any distinct line of demarcation between it and 

 the fibrous connective tissue. Beneath the reflector is a 

 layer of pigment, and at each side is pigment partly con- 

 nected with that below. There are several blood-vessels 

 in the fibrous connective tissue, but the exact point of con- 

 necting with the organ could not be made out. 



In the organs of the upper opercular row (fig. 4) the 

 dorsal side of the spicular layer is turned up, and slightly 

 over, making in this acute angle, a sort of pocket. This 

 pocket is filled up with the connective tissue capsule, which 

 is rather thin above the lens. At the ventral side of the 

 organ, posteriorly, is the nourishing blood-vessel. In con- 

 tact with the curved portion of the spicular layer, both 



ESSEX INST. BULLETIN, VOL. XXI. 4 



