454 PROCEEDINGS OF THE NATIONAL MVSlfUM. vol. xxxii. 



cc. Lateral processes of the pubic bone almost wanting, ventral spine short, 

 5-75 in head; dorsal spines very low. Sakhalin, N. Japan. _. P. tijmensis. 

 bit. Anterior part of body with vertical bony plates. 



d. Plates well developed, depth of body 42-51 in total length (without caudal). 



Amur, Vladivostok, Japan, Korea, China (Yang-tse-kiang?)...P. sinensis. 



dd. Plates less developed, depth of body 6 in total length (without caudal). 



Dalai-nor Lake in E. Mongolia ]'. sinensis sienurus. 



ddd. Plates less developed, sometimes on the anterior part of the body inter- 

 rupted or wanting. Kamchatka P. .sinensis 'imssnessenshji. 



act. Caudal peduncle smooth, laterally without keel. 



e. Anterior part of body naked. France, England , P. brvis. 



ee. Anterior part of body more or less protected with vertical bony plates. 

 Many varieties in Black, Caspian, and Aral seas P. jjlatygaster.c 



a Gaslerosicns plati/gaster Kessler, Bull. Soc. Nat. Moscou, XXXII, 1859, Pt. 2, p. 

 202 (Odessa, mouth of Dnieper. ) 



