54^ 



The True Sharks 



haul of the net. They are very destructive to herrings and other 

 food-fishes. Usually the fishermen cut out the hver, throwing 

 the shark overboard to die or to be cast on the beach. In 

 northern Europe and Xew England Sqiialns acanthias is abun- 

 dant. Sqiiahts siicklii replaces it in the waters about Puget 

 Sound, and Sqitalns mitsitkitrii in Japan and Hawaii. Still 

 others are found in Chile and Australia, The species of Sqiialiis 

 live near shore and have the gray color usual among sharks. 

 Allied forms perhaps hardly different from Sqiiahis are found in 

 the Cretaceous rocks and have been described as Coitrophoroides. 

 Other genera related to Sqiialiis live in greater depths, from loo 

 to 600 fathoms, and these are violet -black. Some of the deep- 

 water forms are the smallest of all sharks, scarcely exceeding a 



-Etmopierus lucijer Jordan it Snyder. Misaki, Japan. 



foot in length. Etiiioptcriis spiiiax lives in the [Mediterranean, 



and teeth of a similar species occur in the Italian Pliocene 



rocks. Etuwptcrits liicifcr* a deep-water species of Japan, has a ' 



brilliant luminous glandular area along the sides of the bell3^ 



Other small species of deeper waters belong to the genera 



Centrophorus, Cejitroscyniuus, and Deaiiia. In some of these 



species the scales are highly specialized, pedunculate, or having 



the form of serrated leaves. Some species are Arctic, the others 



are most abundant about ilisaki in Japan and the Madeira 



Islands, two regions especially rich in semibathybial types. 



Allied to the Sqiialidcr is the small family of Oxynotidcr with 



short bodies and strong dorsal spine. Oxyiiotus centrina is found 



in the Mediterranean, and its teeth occur in the Miocene. 



Family Dalatiidee. — The Dalatiidce, or scymnoid sharks, differ 



from the Squalida almost solely in the absence of dorsal spines. 



The smaller species belonging to Dalatias (Scymnorhinus, or 



Scymnus), Dalatias licha, etc., are very much like the dog- 



* Dr. Peter Schmidt has made a sketch of this little shark at night from a 

 living example, using its own light. 



H'f?' (Jf 



