ART. 21. PARASITES OF SHAEKS AND SKATES LINTON. 43 



folds of the pseudoscolex. It seemed to be more mobile than the 

 forms from the tiger shark, while the borders of the bothria appeared 

 to be less rigid. 



1914, August 6 : 1, measuring 115 mm., lying uncompressed in sea 

 water. This specimen was badly macerated, as if affected by the di- 

 gestive juices of the shark. The cestodes with which it was associated 

 in the spiral valve, were living. Greatest breadth, near anterior end 

 5 mm.; breadth of posterior segments 3.5, length 2, compressed; 

 breadth of pseudoscolex 6. When the specimen had been fixed in 

 corrosive-alcohol-acetic, and straightened, it measured 147 mm.; in 

 addition there were fragments aggregating 24 mm. Some of these 

 were stained and mounted in balsam; although much macerated such 

 of the anatomy as can be seen is in agreement with this species. 



1915, July 19: 1, about 30 mm. in length, with medium sized 

 pseudoscolex was collected from a hammerhead shark by Dr. G. A. 

 MacCallam. 



PARATAENIA MEDUSIA Linton. 



1890, pp. 862-866. pi. 15, figs. 5-9. 

 1897a, p. 440. 



1900, p. 275. 



1901, p. 433; figs. 290, 291. 

 1905, p. 347. 



1910a, p. 695. 

 1911, p. 587. 



Records of this cestode not before published : — 



Dcusyhatis centrura. 



Collected in 6 of the years from 1903 to 1922 inclusive. On 1 date 

 in July, 3 from small ray, 1 from large ray. On 3 dates in August : 

 (1) Numerous; (2) 1, length 16mm. ; scolex, length 0.46, breadth 0.49; 

 diameter behind scolex 0.17; distance to first distinct segments 0.14; 

 first segments, length 0.14, breadth 0.19; median segments, length 

 0.58, breadth 0.22; last segment, length 1.12, breadth 0.29. Some 

 free segments, much elongated, and crowed with minute thin-shelled 

 eggs; (3) few. On 3 dates in September: (1) Few; (2) 2, length 

 4.5 mm.; (3) 2. 



1923, July 7 : many ; August 15:1; August 20 : 4. 



(U.S.N.M., Helm. Coll. 7692.) 



ICHTHYOTAENIA ADHERENS, new species. 



Plate 6, figs. 55-59. 



Taenia, species 1901, p. 428 ; figs. 274-282. 

 1911, p. 589. 



On July 31, 1899, a number of these cestodes were found attached 

 to the mucous membrane of the spiral valve of a hammerhead shark 

 at Woods Hole, Mass. About a dozen of them had their heads 



