560 REPORT OF COMMISSIONER OF FISH AND FlSlIEHIKtt. 



men the margins in optical section are creniilate. and tlie body tapers 

 towar'ds each end. 1 can not refer this specimen to any s])ecies with 

 any degTce of certainty. The former encapsuled spo(;iniens are evi- 

 dently yonng forms of those which I have referred provisionally to 

 Ascaris tenuis.sima, although they present some resemblance to Ascaris 

 capstUaria Rudolphi. 



LEUCISCUfc! ATRARIUS. 



The nematods secured from this fish were few in number. They were 

 found only in the body cavity, where they were coiled up under the 

 external tunic of the viscera. They are all apparently larval ascaridtie, 

 although on account of their rudimentary condition I have not been 

 able to identify them with certainty. 



One specimen obtained from the .serous coat of the intestine of its 

 host appeared to be near the stout nematod from A'. myJiiss mentioned 

 above. It was 17 mm. in length. Its greatest breadth was 0.6 mm. 

 near the posterior end. Its diameter at the anterior end was 0.25 mm. 

 The living worm was for the most i)art brownish red in color. When 

 the alcoholic specimen was examined it was found to be partly envel- 

 oped in a thin, tr.msparent, chitinous investment, which, when removed, 

 revealed a smooth cuticle, with a broad, prominent lateral line. The 

 breadth of the lateral lines was about 0.07 mm. at the anterior end, in- 

 creasing to 0.1 mm. toward the posterior end. The surface, except along 

 the lateral regions, presented a reticulated or scpiamose api)earanee. 

 When the specimen was placed in glycerin the reticulations were no 

 longer visible. Fine transverse fibers and strong longitudinal fibers, 

 however, became visible in the cuticle. 



The neck is continuous with the body, the head narrow, truncate, 

 mouth terminal, with rudimentary lips. The body is gradually atten- 

 uate anteriorly, but tapers abruptly and somewhat unequally on 

 opposite sides to the rather blunt posterior end ; anal aperture ternunal. 

 At the posterior end there is a minute, bluntly rounded, papillary 

 spine, 0,012 mm. in length. Nothing could be made out with regard to 

 the oesophagus or genital organs. 



In addition to the above, some small white nematods were obtained 

 from the mesentery. These were about 7 mm. long and 0.35 mm. in the 

 greatest diameter. The anterior en'd is nearly truncate and 0.1 mm. in 

 diameter. The body tapers nearly uniforndy to each extremity, but in 

 some more abruptly towards the posterior end. The lateral lines are 

 prominent. The surface of the body is smooth, the longitudinal nuisdes 

 well developed, giving a longitudinally striated ai>pearance when 

 magnified ; transverse striai are not visible in alcoholic specimens, but 

 become visible wlien treated with glycerin. The number of oral lobes 

 is not delinite, but there are several small oral papilhe. The genital 

 organs are rudimentary, the anal aperture terminal. These specimens 

 resemble the larger specimen closely, but in life were white, while the 



