AKT. 21. PARASITES OF SHARKS AND SKATES LINTON. 35 



many, with many A. laciniatum, and C. angustum^ and 3 P. trilocu- 

 latum; (4) few. in 1 of 3 sharks. On 10 dates in August: (1) 

 many in 150-centimeter shark; (2) few, in 325-centimeter shark; 

 (3) many, in a 302-centimeter shark; (4) 8, with 3 A. lacirdatum^ 

 and 2 C. angustum.^ with very few free proglottides in a 225-centi- 

 meter shark; (5) 45, with 29 A. lacmiatum and 5 O. crcnacolle^ in a 

 150-centimeter shark; (6) 3 in one shark, with 18 A. laciniatum^ and 

 63 in another with 4 A. laciniatwm and 4 G. angustum^ many free 

 proglottides; (7) 1, length 23 mm., and a few free proglottides in 

 1 of 2 240-centimeter sharks; (8) 30, in 165-centimeter shark, no 

 other parasites found; (9) three 165-centimeter sharks from Obed 

 Dagett's trap in Buzzards Bay. No. 1:65, with 6 A. laciniatum, 33 

 C. angustum, and 19 D. pileatum. No. 2:36, with 7 A. laciniatum, 

 19 O. angifstum. No. 3:40, with 1 .4. laciniatum., 2 C. angustum; 

 (10) 9, no other parasites in spiral valve. On 5 dates in September: 



(1) 5, from 10 to 28 mm. in length, from a 150-centimeter shark; 



(2) 12, with 12 A. laciniafum., and over 200 C. angustum; (3) 14, 

 with 95 C. angvstu7n, from 3 small sharks; (4) 185, with 2 A. lucin- 

 iatum, 8 C. angustum, 1 P. cervinum, and many free proglottides, 

 in a 210-centimeter shark; (5), 93, with 9 A. laciniatum, 14 C. 

 angustum, and 1 T. hi-sulcatus, in a 240-centimeter shark. 



Galeocerdo arcticus. 



1915, August 2: 2, with 2 O. paulum, and large numbei*s of T. 

 thysanocephalu7n. 



Scoliodon terrae-novae. 



1914, August 20: 1, length 20 mm., with 40 C. angustum., 2 P. 

 cervinum^ and 1 D. pileatum,, in a 150-centimeter shark. 



1915, July 15 : Many, with a few A. lacmiatum and many C. 

 angustum. 



Vulpecula mmdna. 



1923, July 30: 1, and 2 fragments; lengths, 12, 15, 18 mm. 



August 28: 270 counted; many adhering firmly to mucous mem- 

 brane of spiral valve ; maximum length 32 mm. 



PHOREIOBOTHRIUM TRILOCULATUM Linton. 



Plate 5, Figs. 45-46. 



1901, p. 427, pi. 20. fig. 292. 

 1905, pp. 340, 343. 

 1911, p. 587. 



This species is readily recognized by the three loculi at the pos- 

 terior ends of the bothria. 



Scolex. — Length and breadth about equal; more robust than P. 

 lasium; hooks same general plan as in that species, but much larger, 



