1899] Prince — Paddle-Nosed Sturgeon in Ontario. 157 



the head in Ganoids, between the eyes and the gills, possess a few 

 gill-filaments, and have not lost their branchial function. There 

 is no accessary or opercular gill, such as we find in the Sturgeon 

 and Lepidosteus on the posterior face of the hyoid arch ; but a 

 pseudobranchia distinct from a true opercular gill occurs. In spite 

 of its name Polyodon has no teeth. They are present in the young: 

 but disappear as the fish grows. It is said to frequent only the 

 dark and deeper parts of the rivers and lakes where it occurs, and 

 both on account of its structure and habits is a singular type 

 amongst fishes. It has, as already pointed out, many exceptional 

 features distinguishing it from its Ganoid allies, and would never 

 be ranked by an ordinary observer with the Sturgeon, the Bow-fin 

 [Amia) or the Bony Pike or Bill-fish (Lepidosteus ) of our own 

 waters or with the Polypterus of the Nile and Senegal, or with the 

 African Calamoichthys, from Calabar. To the scientific eye they 

 all belong to one group, one of the most interesting groups in the 

 whole range of Zoology. The Ganoids on the one hand possess 

 features of the Shark tribe (e.g. the many-valved conus arteriosus, 

 the heterocercal tail, and the intestinal valve), while they exhibit 

 features which are equally typical of the Teleosts or Bony Fishes, 

 viz.: free pectinate gills, an operculum, a permanent mesonephros, 

 and the production of small spherical eggs in considerable quantity. 

 They are a generalised type of fishes, and of great antiquity, as 

 geological evidence demonstrates. Hence their morphological 

 and palaaontological importance. 



SALSOLA KALI TRAGUS. 



A few specimens of "Russian Thistle" were found this sum- 

 mer by Mr. W. T. Macoun, the Horticulturist at the Experimental 

 Farm, in a field of Alfalfa sown last year. The Alfalfa seed was 

 purchased in Ottawa, but though the "thistle" has ripened its 

 seed there is no danger of its spreading or becoming the noxious 

 weed it is in the west. It is only on the prairies that it is to be 

 feared. 



