76 PEOCEEDINGS OF THE NATIONAL MUSEUM. vol. 64. 



segments the aperture is circular, in later, ripe proglottides it is 

 more or less elongated. 



Tlie longitudinal excretory vessels are conspicuous, as are also 

 transverse vessels, of which one lay near the base of each pro- 

 glottis. The specimen had been placed in fresh water for a short 

 time, which fact may account for the enlargement of these vessels. 



A curious abnormality in the development of the proglottides was 

 noted about 50 mm. back of the scolex. A sketch of this region is 

 shown in Figure 102, 



One specimen of this cestode was found, on August 5, 1922, in 

 the spiral valve of a 210-centimeter shark, C archarhinus milberti. 

 The stomach of the shark contained fragments of menhaden and 

 a considerable quantity of oil. 



Dimensions of the cestode in life: Length 250 mm.; length of 

 scolex 25, breadth 3.5; length of posterior segments, average of last 

 five, 6.6, breadth 3.8. Length, in balsam, 210; length of scolex 21; 

 breadth of scolex, through divergent bases of bothria, 3, immediately 

 behind bothria, 2, which breadth is maintained to near the base, 

 where it increases to about 3.25. Bothria emarginate, length 2 mm., 

 breadth about the same, or a little more. The ova measure about 

 0.045 by 0.036 in the two principal diameters. 



2V/^e.— U.S.N.M., Helm. Coll. 7705. 



Four large cestodes belonging to this species were found August 6, 

 1923, in the spiral valve of a shark, C archarhinus commeTsonii: Maxi- 

 mum length 420 mm., maximum breadth 6 mm. ; pinkish in median 

 region when strongly contracted, scolex and anterior portion yellow- 

 ish white, posterior yellowish. 



Associated with these strobiles was a slender strobile, length 210 

 mm., linear, breadth 2 mm. ; scolex ivory white, strobile translucent 

 white. The books agree with R. insigne. 



RHYNCHOBOTHRIUM LOMENTACIUM Diesingr- 



1800, pp. 84r»-S47, pi. 33, figs. 1-?.. 



1911, p. 588. 

 Adult stage. 

 Galeorhinus laevis. 

 1905, July 31: Fragments of strobile, referred to this species. 



RHYNCHOBOTHRIUM LONGICORNE Linton. 



1890, pp. 847-849, pi. 13, figs. 4^8. 

 18970, p. 450. 

 1901, p. 429. 

 1911, p. 588. 

 Adult stage. 

 Garcharias taurus. 



1904, July 19 : 2 scoleces, and a few free proglottides. 

 (U.S.N.M., Helm. Coll. 7706.) 



