ACIPEXSER XACCAEIT. 



im 



and have strong- keels, each prolonged into a baekwardly directed spine. 

 Behind the dorsal fin is a double row of three or four small shields, or there 

 may be a large long one and two smaller. The lateral line is covered by 

 forty long lozenge-shaped shields, twice as deep as long, with straight spines. 

 There are ten shields in the ventral row, which extends as far as the ventral 

 fin, and behind it there is a further series of ten, which may number nine or 

 eleven on one side. 



There are two keeled shields between the ventral and anal fins, the more 



Fio-. 19li 



PPEK SUKFACE OF HEAD 

 'ENSEK NACCAllII. 



Fig. 193. — UPPER SURFACE OF HEAD 

 ACIPENSER NACCARII. VAR. XARDOI 



anterior of which is the largest of all the shields. There is generally a long 

 shield, without a keel, behind the anal fin. Between the rows of shields the 

 skin is covered with starlike scales which vary in size; anterior to the pectoral 

 fin they hav^e a regular lozenge shape. The bony ray of the pectoral fin is 

 strong, and longer than the breadth of the head over the squamosal bones. 

 There are thirty-two to thirty-five truncate rays on the upper margin of the 

 upper lobe of the caudal fin. There is a small rayed shield in front of the 

 base of each of the ventral fins. 



