AET. 21. PARASITES OF SHARKS AND SKATES LINTON. 57 



sea water, when each of them immediately turned and thrust its pro- 

 boscides through its own body ; length 35 mm., breadth 5. 

 Xiphias gladius. 



1904, July 15: Many, in body cavity on viscera and peritoneum, 

 in each of 3 swordfish. When placed in sea water they contracted to 

 30 mm., or less, and elongated to 100 mm., or more. These larvae are 

 not encysted, but are wandering under the serous membrane of the 

 viscera and body wall. One of the fish had many of the copepod 

 parasite, Penella plumosa, burrowing into the flesh, some of them 

 penetrating into the body cavity, where their heads were encysted. 

 More internal parasites were found in this fish than in either of the 

 others. 



July 20 : Many, in body cavity of each of 3 swordfish. 



July 28 : Many, on peritoneum of 1 swordfish. 



1911, July 13: 40 from one swordfish, 8 from another; on viscera 

 and peritoneum; probably not all collected; most of them white, onc^ 

 decidedly yellow; very contractile. 



1912, July 20 : 2, from viscera of 1 swordfish. 



1913, July 7 : Many, on viscera and peritoneum of 1 swordfish. 

 1920, July 27: About 10, from each of 2 swordfish; viscera and 



peritoneum. After lying in sea water for some hours they became 

 much elongated, one of them measuring 150 mm. 

 (U.S.N.M., Helm.€oll. 7732.) 



RHYNCHOBOTHRIUM BULBIFER Linton. 



1889&, R. tenuicolle Rudolphi, pp. 486-488, pi. 5, figs. 17, 18. 



1890, R. bulbifer Linton, S25-829, pi. 10, figs. 8, 9, pi. 11, figs. 1, 2. 



18970, p. 448. 



1900, p. 270. 



1901, pp. 425, 436, 445, 447, 451, 460, 464, 482. 

 1910a, pp. 1201, 1202. 



Adult stage. 



The length of the hooks near the base of the proboscis greater than 

 that given in the original description, being about 0.03 mm. 

 Gcdeorhinus laevis. 



Collected in 7 of the years from 1903 to 1915, inclusive: On 5 

 dates in May, 5 to 75 strobiles, with from few to many free proglot- 

 tides, 8 dogfish examined; 6 dates in June, 4 to 80 strobiles, fi*ee 

 proglottides found on some of the dates, 24 dogfish examined ; 7 dates 

 in July, 4 to 100 strobiles, 9 dogfish examined ; 9 dates in August , 2 

 to 6 strobiles, 9 dogfish examined ; 2 dates in September, 1 and free 

 proglottides from 1 dogfish on 1 date, 2 in 1 of 2 dogfish on the other. 



(U.S.N.M., Helm. Coll. 7699.) 

 Squalus acanthias. 



1904, June 6 : 32, and free proglottides, from 4 dogfish. 



1910, July 29 : 3. 



