TREMATODES FROM FISHES — LINTON 6 



0.07 mm. The anterior end is bilobed, each lobe bearing a small con- 

 tractile papilla. The posterior sucker bears two larger hooks sym- 

 metrically placed, one on each side of the median line, and about 

 18 small hooks and 2 spines on the margins. 



These worms perform active looping movements, attaching them- 

 selves by the anterior end; then, releasing the posterior sucker, they 

 rapidly loop themselves forward. 



Subfamily Tetraonchinae Monticelli, 1903 

 Genus ANCYROCEPHALUS Creplin, 1838 



ANCYROCEPHALUS PARVUS, new species 



Plate 14, Figtjees 159, 160 



Body elliptical, narrowed abruptly at anterior end, which bears 

 four blunt projections, and two pairs of eye spots; pharynx longer 

 than broad ; posterior disk with 18 hooks, 4 median pairs, 5 hooks on 

 each lateral margin, and 2 transverse bars. The two median hooks 

 are somewhat larger than the others. The cirrus pouch is pyriform, 

 the cirrus long and filiform; seminal vesicle long-pyriform, beside 

 cirrus pouch, ventral and posterior to the pharynx. Ovary median, 

 longer than broad ; seminal receptacle on left side at anterior border 

 of vitellaria ; follicles of vitellaria dense, filling all but a small portion 

 of the anterior end of the body from the margins to the ovary and 

 testis on the median line, and extending to the posterior end. One 

 testis, longer than broad, on median line behind the ovary. Measure- 

 ments in balsam : Length, 0.73 mm. ; breadth, anterior end 0.1 nam., 

 middle 0.5 mm. ; pharynx, length 0.07 mm., breadth, 0.05 mm. ; length 

 of longest hooks 0.024 mm. 



Average of 5: Length, 0.82 mm.; breadth, 0.38 mm. Longest, 

 length 1.08 mm., breadth 0.34 mm. ; shortest, length 0.67, breadth 

 0.39 mm. 



Measurements, life (U.S.N.M. No. 8143) : Length, 0.84 mm.; 

 breadth, anterior (head) 0.1 mm., middle, maximum, 0.42 mm., 

 posterior (caudal disk) 0.14 mm. 



The middle of the body was traversed by strong, longitudinal 

 muscle fibers, and by less strong longitudinal fibers along the lateral 

 margins. The head carried four club-shaped projections, which, in 

 a specimen fixed over the flame, broke up into longitudinal striae. 



Type specimens. — ^U.S.N.M. No. 8143 (holotype and paratypes) . 



Host. — Garfish {Strongylura marina). 



Record of collection. — Ten, collected on August 30, 1911, from 

 gills of host. 



