FISH PARASITES COLLECTED AT WOODS HOLE. 297 



Cysts -with Treniatode Ova. 



[Plato 40, figs. 82-84, U. S. N. M. No. 0.123.] 



Three specimens of white perch (Mnrone am erica n a), examined on August 27, had tlie viscera 

 generally covered with pigment patches. A study of these not, only verified observations of a similar 

 nature published by mo in vol. xx, Proceedings of II. S. National Museum, page 537, but confirmed 

 eerlain conclusions reached with regard to some waxy masses found in a diseased ovary of this fish. 



In the specimens ova were found (1) with cyst just beginning; (2) with thick cyst of connect iv 

 tissue; (3) cyst and ovum both surrounded ^vith a waxy secretion, but ovum still plainly visible; 

 (4) a waxy mass similar in appearance to (3) but with no ovum visible; (5) masses of very dark-bro\\ n. 

 almost black, pigment. The ova were not of uniform size; the largest, however, measured O.Oi'ii mm. 

 and 0.013 mm. in the two principal diameters shown in optical section. 



Sections of the liver were made, but no pathological features were noted further than presence 

 of ova in pigment patches, of which there were a largo number in the serous coat of the liver. 101) ova 

 were estimated in a single section through one of these pigment patches, which would indicate 

 approximately 4,000 ova in the pigment patch. 



Gasterostomum ovatum Lt. 



[Monostomwn orbic-idarc Rmlolplii, Linfon, Proe. TT. S. N. M., vol. XX, pp. .141-542, PI. LIV, figs. 2-5. U. S. N. M. No. 4872.] 



The specimens from Lnbofcx purinamensis, referred by me to the genus Monostomum, belong to the 

 genus Gasterostomum. As they appear to be new, I propose the name (fafsteroxtotimm oratum for the 

 species, and give the following emended definition: 



I'.ody ovate, depressed, flattened ventrally, convex dorsally. Acetabulum subterminal a little 

 broader than long. Mouth [fig. 3, ph., loc. cit.] at about anterior fourth of body. The mouth is easily 

 overlooked. When a specimen is placed in a transparent medium a subglobular pharynx is seen, in 

 appearance like a small ventral sucker. Vitellaria arranged inasomewhat semicircular band between 

 the mouth and acetabulum along the right side as far as the first testis, and along half the length of 

 the left side. Testes two, subglobular on the right side back of the mouth, and one following the 

 other closely. Ovary globular in front of testes and beside the mouth. Uterus voluminous, crowded 

 with small, nearly globular Ova, its folds lying along the left side and midventral line from a point a 

 little in front of the mouth to near the posterior end, where there is a large roundish mass of ova, 

 which in ventral view usually obscures the oblong ovate cirrus pouch. The latter lies near the 

 mid-ventral line, its base on a level with the posterior edge of posterior testis. The external genital 

 aperture is at the posterior end. 



Additional measurements, in millimeters: Length 1.91, greatest breadth (at mouth) 0.92; length 

 of acetabulum 0.17, breadth of same 0.2; breadth of mouth 0.07; diameter of oral sucker (pharynx of 

 original description) 0.14; length of anterior testis 0.25, breadth of same 0.21; length of posterior 

 testis 0.21, breadth of same 0.25; diameter of ovary 0.17; diameter of ova (average) about 0.017; 

 distance between acetabulum and month (centers) 0.56. 



Gasterostomum arcuatum sp. nov. 



[Plato 41, figs. 85-90, TT. S. N. M. No. 6524.] 



On two occasions small trematodes were found in the bonito (Sarda narda) .Tnly 20 numerous, 

 August 8 few in pyloric c;eca and intestine. In the living worm the color of the lateral margins is 

 translucent white, anterior yellowish white, posterior yellowish brown where the ova show through 

 the body wall; neck very changeable, contracting and extending incessantly. These prove to belong 

 to the genus (lastcrostominn. 



The following description is based on preserved specimens: Body slender, cylindrical, tapering 

 gracefully to anterior end, arcuate; posterior end bluntly rounded, covered with minute, low, Hat 

 spines, which are dense in front and throughout the greater part of the length of the body; anterior 

 sucker terminal with circular aperture, ; ventral sucker (mouth) situated little in advance of middle, 

 smaller than anterior sucker, globular; aperture subcircular; intestine short, soon expanding into a 



