ART. 21. PARASITES OF SHARKS AND SKATES LINTON. 49 



Cestracion zygaena. 



1908, August 27: 3, and numerous ripe proglottides free in the 

 chyle of the spiral valve. 



1912, August 9 : Few, with free, ripe proglottides. The shark had 

 been harpooned by Mr. Charles Grinnell on the 8th, and was not 

 examined until the next day. The cestodes were somewhat macer- 

 ated, but some of the ripe segments were still active. 



1913, August 1 : 2. 



1914, August 7: Many, and large numbers of free, ripe proglot- 

 tides, which were slender, wormlike, and active, even after lying for 

 some time in sea water. 



(U.S.N.M., Helm. Coll. 7695.) 



Larval stage. 



Caranx chrysos. 



1910, September 22: 1, from small piece of stomach in vial. 

 Carcharhinus limbatus. 



1915, August 6: Encysted in large numbers in submucosa of 

 stomach. 



1918, July 13: Very numerous in submucosa of stomach. 

 1923, July 28 : Numerous, in submucosa of stomach. 

 € archarhiriKs ohsmirus. (See p. 7.) 



1907, August 3 : Few, in amber colored cysts in stomach wall. 



1911, August 3 : Bather numerous, in submucous coat of stomach, 

 most abundant near posterior end of cardiac portion. Some of the 

 cysts were yellow, on account of the presence of degenerate tissue. 



1912, September 12: Large numbers of cysts in submucosa of 

 stomach; oval-elliptical, 1 to 1.5 mm. in diameter; submucosa of en- 

 tire stomach thickly covered with these cysts, estimated to average 

 50 to the square inch. 



1914, September 1 : Cysts in stomach wall in enormous numbers. 

 The stomach was examined in several places and these cysts were 

 found in great nimibers in all of them, most numerous at pyloric 

 end. It was estimated that there were 12 cysts to every square 

 centimeter of surface. The cysts were mostly yellowish, some were 

 yellowish brown, and contained only degenerate tissue. Cysts which 

 contain the characteristic scoleces of this cestode are from 1 to 2 mm. 

 in the longer diameter. What was at first taken to be a cyst, 6 mm. 

 ■n diameter, on the intestine of this shark, proved to be a small 

 outfolding of the mucous membrane, filled with chyle. Its com- 

 munication with the lumen of the intestine was nearly occluded. 



1918, August 20: Cysts in submucosa of stomach, not numerous. 



C. commei'sonii. 



1923, August 25 : Great numbers of cysts in mucous membrane of 

 stomach of 184-centimeter shark, 100 cysts of 0. crenacolle and one 



