THE COMMON BRITISH STURGEON. 17 



other. Heckel and Kner describe the middle lateral 

 shields of their Ac. sturio as having' a styloid process 

 which proceeds forwards beneath the skin to the pre- 

 ceding shield, and is said to be characteristic of the 

 species ; but in the Frith of Forth Sturgeons no such 

 process exists in any one of the whole lateral series, there 

 being merely a notch with a flexible tube, corresponding 

 to the lateral line of osseous fishes. There is, however, 

 a strong and distinct smooth styloid process from the 

 front of all the ventral shields of the Frith of Forth spe- 

 cimens, except the first two of the series. These ventral 

 shields are also unequal in number, on the two sides of 

 the fish, and vary in the specimens from nine to eleven. 



The skin between the dorsal and lateral rows of shields 

 is pretty thickly studded with star-like ossicles, inter- 

 mingled with much more minute angular grains. A 

 cluster of these ossicles is represented under the prece- 

 ding wood-cut. A pair of small shields intervenes be- 

 tween the dorsal series and the dorsal fin, and on each 

 side of the base of this fin there are about ten star-like 

 ossicles larger than the others. Below the lateral shields 

 the distinctly-stellate ossicles become fewer, and the irre- 

 gular, crested grains more numerous. Between the limbs 

 of the coracoids, and more especially a little further back 

 below the pectorals, the skin is made rough by extremely 

 irregular ossicles, apparently formed by the confluence of 

 several minute angular grains and acute points, and this 

 roughness continues onwards to the vent. The integu- 

 ment before the opercular shield is studded with small 

 roundish and irregular plates, all with radiating lines 

 from flat centres, and small plates of more oblong forms, 

 but various outlines roughen the surface between the 

 mouth and the coracoids. 



The dorsal fin is supported by forty-one rays, the first 



VOL. II. (2nd Snpp.) F 



