PARASITES OF FISHES OF THE WOODS HOLE REGION. 
483 
than in the forms upon which that species was based. No spines were noted, but the body was 
crossed by line transverse stria. Dimensions of living specimen in millimeters: Length, 1.19; 
diameter, anterior 0.08, middle 0.23, of oral sucker 0.07, of acetabulum 0.07; ova, 0.052 and 0.034 in the 
two principal diameters. Spherical bodies were noted in the excretory vessels. Associated with this 
distome were two smaller, oval, minutely spinose distomes. Dimensions, life, in millimeters: Length, 
0.73; diameter, a-nterior 0.1, middle 0.34, of anterior sucker 0.07, acetabulum 0.08; ova, 0.065 and 
0.04 mm. in the two principal diameters; diameter of spherical bodies, 0.02. An immature distome 
collected August 30 probably belongs to this species (fig. 345). Some of these small oval distomes 
resemble I), pyriforme. 
22. Distomum dentaturn Linton. Intestine. 7, pp. 283, 294, pi. xxxix, figs. 64-67. 
Found on seven different dates in 1899. July 26, 1900, adults with ova, smaller without; the 
young were relatively much more slender than the adults. August 9, 1 900; numerous. August 10, 1900; 
about 12, large and small. The following note was made at the time of collecting the specimens referred 
to this species on August 9: Younger specimens translucent, bluish, older specimens yellowish. A few 
of the older ones without spines thought at first to be different species. Seen by making comparative 
measurements to be the same except for the matter of spines, and that the ova in the spineless ones 
seemed to be a little larger. Either these spineless forms will prove to belong to some species like 
D. vitellosum or D. simplex or they will have to be regarded as examples of T>. dentaturn which have 
lost not only the large spines from the mouth, but the smaller spines from the body as well. A 
reexamination of these specimens leads me to conclude that those which do not have the spines around 
the mouth belong to this species. The oral spines are evidently lost in the older worms. Three 
distomes collected August 14, 1899, were thought at first to belong to a different species, on account of 
what appeared to be a peculiarity in the structure of the oral spines. These appeared to be directed 
forward and to be hastate in shape. This appearance was later found to be due to the fact that the 
oral sucker was everted to such an extent as to bring the bases of the spines in focus first. The only 
important differences observable between these specimens and the I), dentaturn as originally described 
is that the opening of the acetabulum is round instead of transverse, and the pharynx pyriform, broader 
than long, in alcoholic specimens, but such characters should be given little weight in the determination 
of distomes. The following measurements are given for the purpose of comparison with those given 
in the description of the species. Dimensions of living specimen in millimeters: Length, 2.86; diameter 
at anterior sucker 0.29, at acetabulum 0.76, middle 0.75, posterior 0.42; oral sucker, length 0.24, 
breadth 0.24; acetabulum, length 0.23, breadth 0.24; pharynx, length 0.19, breadth 0.18; length of 
oral spines, longer 0.03, shorter 0.02; length of body spines, 0.017; ova, 0.079 and 0.041 in the two 
principal diameters. Dimensions of alcoholic specimen in millimeters: Length, 2.03; transverse 
diameter of oral sucker 0.17, of acetabulum 0.2; pharynx, length 0.1, breadth 0.16; ova, length from 
0. 055 to 0.072, breadth 0.038 to 0.041 ; anterior border of acetabulum 0.5 from anterior end. The distome 
noted in 7, p. 296, pi. xl, figs. 73-75, may be a specimen of D. dentaturn which has lost the oral spines. 
KIIYNCHOBDELLIDA. 
23. Leech. From mouth. This is probably a young specimen of Pontobdella rapu r Verrill. See under 
tSteuotornus, No. 14. 
' The specimen was red when first seen. After lying overnight in water it became yellowish 
green, and when put in Gilson’s mecuro-nitric solution changed to a decided grass-green. July 24, 
1899. Dimensions in millimeters, alcoholic: Length, 8.25; diameter (maximum) of body 0.42, of 
posterior sucker 0.57, of anterior sucker 0.42, of neck 0.28. 
Paralichthys oblongus, Four-spotted Flounder. 
POOD. 
August 5, 1899; 4. Taken in the trawl in about 30 fathoms of water off Gay Head: Shrimps, 
amphipods, and other small crustaceans, annelids, a small lamellibranch mollusk, shell of Utriculus 
canaliculatus, and another univalve shell with a worm tube on it in alimentary tracts. Aug. 16, 1899; 4. . 
Large numbers of amphipods, shrimps, etc., a few small crabs, and small fish in alimentary tracts. 
August 2, 1900; 4. Taken in Muskeget Channel. Small crabs ( Cancer ) and shrimps in stomach. 
ACANTKOCEPHALA. 
1. Ecliinorhynchus acus Rudolph!. Intestine. Aug. 16, 1899; 1. See 8, p. 525, etc. 
