PARASITES OF FISHES OF THE WOODS HOLE REGION. 449 



Decapterus macarellus, Mackinl Scad. 



Only young specimens, 5 inches ami under, liave lieen examined. ( 'opepods found in alinientarv 

 canals of most of them; annelids were found in one lot along with copepods; about 200 fish examined 

 in July and August, 1899 and 1900. 



CKSTODES. 



1. Ceslade larm. Intestines. [PI. .\x, fig. 228, a-e.] 



Shaped something like a spool, with flaring sharp-edged flanges, but changing its shape in a 

 remarkable manner, and its lengtli from 1 to 4 mm. September 1, 1900. 



2. Dirvcd eeslodes {iScolex po!ym(rrj>liii>i DiiiariMn). Small. Free in intestine. See 4, pp. 7<S9-792. 



Found in eight out of nine lots examined. Two red spots in neck and a single costa on the bothria 

 in specimens collected September 1, 1900. 



3. HJiiincliiiliiithrivm (?). Inunature larva^ in cysts on viscera. July 31, 1H99. 



4. Ti tr'ivliiiiirlinx liimdmfiis hmtcm. Cyst on viscera. [PI. xxi, fig. 243.] 



A single scolex, collected August 18, 1900, resembles this species, except tliat tlie liooks are 

 rather more slender. The borders of the_ bothria were provided with a band of very minute, dense, 

 bristle-like spines. Calcareous bodies unusually aliundant, mostly oblong-elliptical in outline and 

 uniforndy distributed in the parenchyma; largest 0.024 mm. in ]irincipal diameter. Diameter of 

 proljoscis, int'luding hooks, 0.06 mm.; w'ithout hooks, 0.034 mm. Length of hooks, 0.024 mm. 



TREM.\TODES. 



5. Distuiiiiiiii (ippeiidindatiim Ruclolplii. Intestine. [PI. xxviii, figs. 312-314.] See 7, |>. 289, jil. 



XXXVI, figs. 25, 26. July 31 and Aug. 2, 1899. Aug. 18 and 22, 1900; few. 

 These distomes were very active, and when stretched to their extreme length becanie almost 

 filiform, except in the vicinity of the suckers. As these worms contract very much when they are placed 

 in the killing fluid, unless kept compressed, but litt>le idea of their appearance in life can lie gained from 

 a study of alcoholic specimens. One of these distomes taken August 22, 1900, revealed a structure 

 of the vitellaria, which suggested 1). moniicellii. It wa.s one of the smaller distomes of the lot and 

 differed in general appearance from the larger principally in the absence of ova (see flgs. 313 and 314). 

 The dimensions of the ova in these ' distomes differ from those which I have recorded for D. iijtpeiidi- 

 cididiim in my report for 1S98 [7, p. 289]. Dimensions in millimetens, life: Length 2.47; diameter of 

 oral sucker 0.15, of ventral 0.35; ova, 0.014 anil 0.01 in the two principal diameters. 



6. Distomum ntldlomm Linton. See 7, p. 290. Aug. 2, 1899; Aug. 29, 1900. 



Two distomes on former date and one on latter, with prominent acetabnia, belong to the species 

 referred to in this paper under this specific name. The one taken August 29 was com]iared with 

 specimens from a young l:)lue-fish taken on the same day, while the worms were alive, and found to 

 agree specifically. 



Trachurops crunieuopbthalmus, Hig-iijid Siml. 



Two small specimens examined August 15, 1X99, liad in tlie alimentary tracts tlie jaws, spines, 

 and other fragments of annelids. 



NEMATODKS. 



1. Innimturi: (Ascarix). Kncapsuled. 



TKEM.\TODES. 



2. DiMomwm appeiidlculatiiiii Rudolphi. See 7, p. 289, ])I. xxxvi, figs. 25, 26. 



This is a small specimen. Length, in alcohol, 0.65 mm.; diameter, 0.26 nun. It appears to 

 belong to the species recorded in this paper as D. appendiculatum. 



r. C. B. 1899—29 



