34 PEOCEEDINGS OF THE NATIONAL MUSEUM vol. 70 



From the black-backed gull {Larus marinus) : 



There is one slide in the collection. It contains 8 fragments of 

 strobiles, three of them with soleces. They agree with the species 

 from the herring gull in number, size and shape of hooks, in the 

 dimensions and character of the scolex, and in the anatomy of the 

 proglottides, so far as it is shown. Breadth of scolex 0.25 mm., 

 diameter of sucker 0.14, length of hooks 0.036; length of maturest 

 proglottides 0.07, breadth 0.50. Genital pores unilateral; cirrus- 

 pouch cylindrical, more or less spirally curved, extending to, or 

 beyond, the median line. All fragments small, and rather delicate. 



RECORD OF COLLECTIONS 



Lar'us argentatuss 



(U.S.N.M., Helm Coll. 7874 (type).) 

 1905, May 4. — Several anterior ends of strobiles, 1 scolex. 

 1912, February 16. — Ten slender strobiles. 



1912, February 17. — Five scoleces; small, slender strobiles. 



1913, February 12. — One, length 13 mm., scolex missing. 

 1913, November 13. — Many fragments of strobiles, scoleces 



missing. 

 1913, November 17. — One scolex. 



1913, November 18. — Three scoleces; several strobiles, scoleces 

 missing. 



1914, January 20. — Two scoleces, one with slender strobile. 



1915, April 8. — One hundred strobiles, more or less, and a few 

 scoleces; small, fragile, much broken, longest about 16 mm. 



1915, October 5. — Three scoleces, diameter 0.22 mm.; length of 

 strobile 15. 



1916, February 17. — Two small fragments. 



1916, April 18. — One hundred and forty-one scoleces from young 

 herring gull; maximum length of strobile about 25 mm.; 

 many fragments of strobiles, a few of them consisting of 

 mature segments very loosely attached to each other. 



1917, January 8. — Four very small, immature, with scoleces; 

 maximum length 12 mm. 



Larus m annus: 



1914. April 28. — A few small strobiles, about 15 mm. in length. 



HYMENOLEPIS FUSUS (Krabb) 

 Figures 102-104 



/Scolex. — Small, suckers nearly circular in outline, rostellum rela- 

 tively stout, hooks strongly recurved, 10, about 0.02 mm. in length. 



Strohile. — All the strobiles in the collection are immature. In all 

 cases they r.re slender, the maximum breadth not exceeding 0.35 mm.. 



