PARASITES OP FISHES OF THE WOODS HOLE REGION. 
445 
CESTODES. 
2. Larval cestodes (. Scolex polymorphic Dujarclin). Small. Free in intestine. Aug. 2 and 3, 1899; 
July 9, 1900; numerous. For account of similar forms, see 4, pp. 789-792. 
3. Dibothrium sp. Young and larva. Intestines. July 9, 1900; a young specimen with about a dozen 
segments, very active; resembles Dibothrium punctatum ( 2 , p. 731). Also a flask-shaped larva 
2 mm. in length when at rest, but capable of stretching to much greater length. 
4. Rhynchobothrium imparispine Linton. Encysted. 4, p. 800. 
5. Rhynchobothrium speciosum Linton. Encysted. 4, p. 802. 
6. Rhynchobothrium bulbifer Linton. [PI. xxi, fig. 244.] Aug. 2, 1899. Encysted in muscles of back. 
TKEMATODES. 
7. Distomum viteUosum Linton. See 7, p. 290, pi. xxxvii, figs. 38, 39. Aug. 2, 1899; July 9, 1900. 
A few small distomes which agree with this species in essential characters were seen on the two 
dates given. These were very active and assumed such a great variety of shapes that they can not be 
characterized briefly. Within the space of a second or two the length may change from 0.7 mm., for 
example, to three times that length or more. The vitellaria are opaque dead-white, other portions 
translucent bluish-white. Ova, few', rather large, dimensions the same as those given for I). vitellosum. 
In death the worms are cylindrical, acetabulum prominent, neck sometimes reflexed. This remark 
applies to those distomes which in this paper are referred to this species. The characteristic subangular 
appearance of the vitellaria is not evident in the living specimens. 
8. Distomum appendiculatum Rudolphi. Aug. 2, 1899; few. Aug. 12, 1899; 30. 7, j>. 289, pb xxxvi, 
figs. 25, 26. 
These appendiculate distomes agree exactly with those from the flounder, which were referred 
with much hesitation to D. appendiculatum. 
Gymnosarda pelamys, Ocean Bonito. 
1. Tristomum licve Verrill. Gills. 6, p. 509, pi. xl, figs. 7, 8. 
Thunnus thynnus, Horse Mackerel. 
FOOD. 
I had no opportunity to examine this fish for parasites until the summer of 1900. On July 16 the 
head (weight, 184 pounds) and viscera of a specimen, taken in a fish trap at Menemsha Bight, on 
the 14th were brought to Woods Hole. The only indication of the character of the food was the jaw 
of a squid in the intestine. The only entozoa were two distomes in the stomach. 
TKEMATODES. 
1. Distomum clavatum Rudolphi. 
Larger specimen 17 mm. long and 7 mm. in greatest diameter. The smaller was 15 mm. and 
5 mm. in the corresponding dimensions. See 6, pp. 539-540, pi. liii, figs. 8-11. 
Sarda sarda, Bonito. 
FOOD. 
The stomachs of bonitos which I have examined have usually been empty, but occasionally I 
have found fragments of fish and squid in the alimentary canal. See also 7 , pp. 277-278. 
NEMATODES. 
1. Ascaris sp. [PI. v, figs. 37-40.] 
Eight in stomach of one fish July 15, 1899. Length of male, 25 mm.; of female, 40 mm. Anal 
papillae much as in A.liabena. On each side there are 5 small postanal pajnllfe and 10 small preceded 
by at least 20 larger preanal papillae. The jaws are prominent and two-toothed. The cuticle was 
imperfect in most of the specimens, as if it had been attacked by the digestive fluids. 
