AUT. 21. PARASITES OF SHARKS AND SKATES LINTON. 27 



cestodes were small, longest 3.5 mm.; length of bothrium 0.48, 

 breadth 0.45 mm.; (2) 1. On 5 dates in October: (1) A few small, 

 slender segments; (2) to (5) 1 on each of 4 dates, 6 to 9 mm. in 

 length. On 1 date in November, 12, all small, less than 10 mm. in 

 length. 



(U.S.N.M., Helm. Coll. 7678-7679.) 



Family ONCHOBOTHRIIDAE. 



Following are records of collections of cestodes belonging to this 

 family made since the publication of my report on Parasites of 

 Fishes of the Woods Hole Region (1901). 



The genera represented are: Acanthohothriwm, CalliohothHum, 

 Onchobothrium^ Phoreiohothnum^ and Platyhothrimn, all of which 

 bear structureless, chitinous hooks on the bothria. The genus 

 Thysanocephalum does not belong in this group. The hooks in 

 that genus, instead of being structureless, have a very dense striated 

 structure, and appear to be a modification of the dense, muscular 

 border of the bothria. 



CALLIOBOTHRIUM ESCHRICHTII van Beneden. 



1890, pp. 812-816, pi. 7, figs. 5-12. 

 1897a, pp. 447, 448. 

 1910O, p. 9. 

 1911, p. 585. 



Records of this cestocle not before published : 



Host; Galeorhinus laevis. Smooth Dog-fish; spiral valve. 



July 9, 1904 : 2. 



July 31, 1905 : 1. 



August 4, 1905 : 1. 



August 5, 1905 : Few, maximum 10 mm. 



August 18, 1905 : Few. 



(U.S.N.M., Helm. Coll. 7680.) 



CALLIOBOTHRIUM VERTICILLATUM (Rudolphi). 



18S9&, pp. 476^79, pi. 4, figs. 1-8. 



1890, pp. 810-812. 



1897a, p. 447, pi. 34, figs. 6, 7. 



1900, p. 270. 



1901, p. 425. 

 1910a, p. 694. 

 1911, p. 585. 



Records of this cestode not hitherto published. 



Galeorhinus laevis. 



Usually present in the spiral valve of the smooth dogfish. Col- 

 lections made in 8 of the years from 1903 to 1922, inclusive. Free, 

 ripe proglottides present in most instances. Thus, on August 18, 



