46 PEOCEEDINGS OF THE NATIONAL MUSEUM. vol.64. 



proglottis, on the median line, about on a level with the genital pore. 

 The eggs are relatively large, for the most part nearlv spherical, and 

 are provided with very thick shells. In an egg measuring 0.18 mm. 

 in diameter, the thickness of the shell was 0.012. All of the ova 

 seen were segmenting. The largest number of nucleated cells noted 

 m any section of an egg was 24. 



DISCOOEPHALUM PILEATUM Linton. 



Plate 1, fig. 7. 



1890, pp. 781-787, pi. 10. figs. 1-7. 



1900, p. 272. 



1901, p. 427. 



1907d, p. 97, pi. 5, fig. 31. 

 1907e, p. 116. 



1908?>, pp. 168-1G9, pi. 1, fig. 8. 

 1911, p. 586. 



Hosts : Oarcharhinus commersonii, Woods Hole, Mass. 

 limhatus. Woods Hole, Mass. 

 milherti^ Woods Hole, Mass. 

 obscurus, Woods Hole, Mass. 

 platyodon, Bermuda and Tortugas. 

 ScoUodon te^rae-novae, Woods Hole, Mass. 



Following are records of this cestode not before published : 

 Oarcharhinus commersonii. 



1923, August 4: 1, length 410 mm.; maximum breadth, 8 mm. 

 Carcharhimis limhatus. 



1918, July 13: 14, attached to anterior third of wall of spiral 

 valve of a 210 centimeter shark; length of smallest, 65 mm., one of 

 the largest measured 450 mm. in length. 



Oarcharhinus milberti. 



^1915, August 12: 4, large specimens with ripe proglottides, at- 

 tached at anterior end of spiral valve, from one of six sharks ex- 

 amined on this date. The scoleces of these cestodes, in shape some- 

 thmg like a mushroom-anchor, have invariably been found firmly 

 attached to the wall of the intestine, the muscular disk penetrating 

 the mucous membrane, and removable only by dissection. Length 

 variable, in sea water about 500 mm., and' 10 mm. broad at wid^est 

 part; segments toward posterior end have a tendency to become nar- 

 rower; no free segments were seen. Enormous numbers of eggs 

 were discharged. In a short time the bottom of the dish in which 

 the worms were lying, was covered with ova, which, at first, were 

 white, but shortly became dark colored. These ova were segment- 



