THE COMMON BRITISH STURGEON. 19 



been nearly one-third larger than the one in the Edin- 

 burgh University Museum described above. 



Another perfect specimen of smaller size, being only 

 three feet eight inches and a half long, preserved in the 

 Museum of the Free Kirk College of Edinburgh, presents 

 also a close similarity in the cranial plates to the two 

 preceding, but the squamosals are both united to the 

 temporals, and the mastoids have consequently smaller 

 disks. In this younger fish the pits and furrows in the 

 shields are deeper and more distinctly radiated from 

 osseous centres. The crests of the dorsal shields are 

 higher, and the styloid anterior processes of the ventral 

 shields are very distinctly perceptible through the skin. 

 The ossicles which stud the skin of the body are more 

 generally and perfectly star-like, more of the rays being 

 acute. There are twenty-nine lateral shields on one side, 

 and thirty-two on the other, and the ventral shields on 

 the right side number ten, bu.t there are only nine on the 

 left side. The fin-rays are 



D. 41: A. 25: P. 1 | 37 : V. 27 or 28. 



The osseous centres of the temporals are equidistant 

 from the tip of the snout with those of the coronals, instead 

 of being a little nearer, as in the other two examples, the 

 difference being probably due to the squamosals having 

 in this example a common centre with the temporals. 

 The snout is also narrower, and the shields covering it 

 are closely pressed together so as to seem confluent. 

 This probably arises from the cartilage not having been 

 so fully cleared out in preparation, and shrinking much 

 in drying. To this cause also may perhaps be attributed 

 the very slender snouts of some of the younger Stur- 

 geons preserved in English Museums. The exact place 

 of capture of this individual is not mentioned on the 



F 2 



