40 



him at West Alton, Mo., in which a fifth of the number were 

 of this species. It is also said by him to occur, as a rule, in 

 swifter water than the common sbovelnose. 



The following table exhibits some of the more important 

 differences observed in comparing our nine specimens of 

 Parascaphirhynchus albus with twenty-one specimens of Scaphi- 

 rhynchus platorhynchus in the Laboratory collection. 



P. albus S. platorhynchus 



Ribs 20 or 21 10 or 1 1 



Ventral radials g 7 



Gill-rakers (points) 2 or 3 2- 5 (usually 4 or 5 



Air-bladder in length head and body 8 5 



Belly and breast naked fully armored 



Sides between scutts scattered 



ossifications 



Depth lateral scutis in length head and body ... . 28 — 32.5 19.8 — 23.8 



Eve in interorbital space 8.3—10 5-3— 8.3 1 (usually 



r ° less than 7) 



Inner barbel in outer 1.7 — 2.9 1.1— 14 



Width mouth in width snout 1.4 — 1.6 1.6 — 1.9 



"Width head in length head 2.5 — 2.9 1.9 — 2.2 



Length head in length head and body 2.9 — 3.2 3.5 — 3.8 



The first of the shovelno.se sturgeons was described in 1820 

 by Rafinesque as Acipenser platorhynchus, and was, in 1835, 

 made by Heckel the type of a new genus distinguished from 

 Acipenser by the absence of spiracles. The first of the Asiatic 

 species was described by Kessler from the Suir-dar in 1872 as 

 JS. fedtschenkoi ; the second, S. kaufmanni,hy Bogdanovin 1875; 

 and the third in 1877 from the Amu-dar as S. hermanni by 

 Kessler, who also discussed and figured Bogdanov's species. A 

 fourth species was described by Nikolsky in 1900 as the type of 

 a new genus, Pseudoscaphirhynchus. Berg ('04) unites the three 

 preceding species under this genus, but does not recognize 

 Nikolsky's species as distinct. 



The American and Asiatic species were first subjected to 

 detailed anatomical analysis by Brutzer ('59) and lwanzow 

 ('87), the memoir of the latter being our fullest treatise on its 

 subject. Zograff wrote in 1887, and again in 1896, especially on 

 the embryonal teeth of these and other cartilaginous ganoids- 



