The Pineal Region in Teleosts. 



343 



Fig. 18. Transverse section through the pineal region of an adult Opsanus. 

 W.U.C, series no. 13, section no. 517. X 21. 



Velum Tnansversum. The appearance of the median lobe of 

 the velum is much the same as that of the 19 mm. larva. The cov- 

 ering epithelium consists of a single layer of long club-shaped 

 cells, grouped into prominent tufts. The larger free end of the cell 

 is often irregular, fringed or lacerated, sometimes rounded and 

 regular. Neither cilia nor cuticulae are present, but long shreds 

 of some substance extend from the ends of the cells into the ven- 

 tricle there to become continuous with a coagulum which is al- 

 ways found close about the velum. In the coagulum are rounded 

 bodies and masses which are stained like the clubbed ends of 

 the cells. The nucleus is located near the free end of the cell 

 and, between it and the base, granules are sometimes to be 

 seen which stain deeply. The epithehum rests upon a rather 

 thick reticular membrane, separating it from numerous underlying 

 blood-vessels, i 



