90 MR. A. D. DARBISHIEE ON THE DIRECTION OF THE 



valve. The gape o£ each gill-slit is much greater than is the case either in 

 the Dogfish or the Skate. The gill-slits themselves appear crowded together 

 in the postero-lateral angle o£ the pharyngeal region, as shown in iig. 2. This 

 crowding is, however, onlj apparent, and is due to the great length of the 

 gill-covers, and especially o£ the anterior ones, as shown in fig. 3. 



Fig. 1. — Dorsal view of Head and Pharyngeal Eegion of Rhina. (| nat. size.) 



Fig. 2. — Ventral view of Head and Pharyngeal Region of Rhina. (f nat. size.) 



What strikes one most, when one looks at a living Rhina resting on the 

 bottom o£ a tank or glass vessel, is its motionlessness. In a full-grown 

 Angel-fish over 2 feet long, not only was there no trace of that regular 

 heaving of the pharyngeal region which is so characteristic a feature of a 

 resting Dogfish or Ray, but no movement of any kind in the anterior region 

 of the body could be discerned. But in two younger Angel-fish the slightest 



