CATOSTEOMI 



631 



larger fifteen-spined Stickleback (Spinachia vulgaris) is entirely 

 marine ; its nests are to be found on our coasts in sheltered rock- 

 pools, and they are made chiefly of sea-weeds and Hydrozoa. 

 Sticklebacks are short-lived, and are believed to breed only once. 



The Gastrosteidae are restricted to the northern hemisphere, 

 being more abundant in the higher latitudes, extending to Ice- 

 land, Greenland, and Bering Straits ; the southernmost points 

 of their distribution are Algeria in the Old "World, and Lower 

 California in the New. 1 



A very large number of species have been described, but 

 probably only about a dozen deserve to stand. 



FIG. 385. Distribution of the Gastrosteidae. 



Fam. 3. Aulorhynchidae. The genera Aulorliynchus and 

 Auliscus, each with one species from the Northern Pacific, much 

 resemble Spinachia in outward form and in the equal size of the 

 anterior vertebrae, but the snout is still more produced, tubiform , 

 and the ventral fins are formed of one spine and four soft rays. 

 The difference which justifies their separation as a distinct family 

 resides in the disposition of the ribs, which are flattened and 

 ankylosed to the lateral bony shields. 



Fam. 4. Protosyngnathidae. This family appears to be 

 intermediate between the Gastrosteidae and the Aulostomatidae, 

 agreeing with the former in possessing slender, free ribs, with 

 the latter in having the first vertebrae elongate, though to a 



1 Dr. Sauvage has described a Gastrosteus texanus, but the locality is probably 

 incorrect, as recent American works do not mention the occurrence of Sticklebacks 

 in Texas. 



