[cooper] TREMATODES FROM MARINE FISHES 183 



fixed and preserved only in 2% formalin (5 of commercial 40% form- 

 aldehyde solution to 95 of water), their walls were poorly preserved 

 and in sections their lumina were indistinguishable at the anterior 

 border of the caudal disc from the numerous parenchymatous spaces 

 of that region. Better preserved material might show, however, 

 that they extend into the caudal disc and are surrounded by the 

 follicles of the appendages of the vitellaria. A comparatively large 

 pigmented spot is situated in the tissue of the ventral surface, im- 

 mediately below the posterior edge of the pharynx. Common genital 

 opening ventral and slightly ahead of the beginning of the intestinal 

 trunks at the hinder end of the first quarter of the distance from the 

 anterior end of the body to the anterior edge of the ovary. It is 

 provided internally with numerous short, stout spines, the largest of 

 which are 0-01 1mm. long and 0-005 mm. broad at their bases. Most 

 of these spines are situated on an anterodorsal muscular elevation 

 which almost completely fills up, at least at certain levels, the whole 

 of the atrium ; a few smaller spines are, however, located on the poste- 

 rior wall, even close around the termination of the vas deferens (Fig. 3). 

 The ovary begins on the right side of the space between the vitellaria 

 and, after taking two short, compact turns towards the right, proceeds 

 to the left, passes forward almost in the median line, backward again, 

 then forward and finally backward to the beginning of the oviduct, 

 the bulk of the organ thus forming two closely applied and somewhat 

 laterally compressed A -shaped portions (Figs. 1 and 4). The ovum 

 at the oocapt measures 0-025 X -014mm. The oviduct, after 

 taking one or two turns laterally or dorsoventrally, is met by the 

 geni to-intestinal canal, the junction of which with a minute median 

 branch of the right intestinal trunk is so small that it appears in only 

 one section of a lO/j, series. The single median vaginal opening is 

 situated dorsally, about two-fifths of the distance from the anterior 

 end of the body to the anterior end of the ovary or about three times 

 as far from the latter as from the common genital opening. It leads 

 into a simple median canal which, after proceeding backwards half 

 way towards the anterior end of the ovary, divides into two vaginal 

 canals which diverge slightly in passing a short distance farther and 

 join the paired yolk-ducts. The latter, parallel for most of their 

 length, converge ventral to the ovary and eventually unite to form a 

 common yolk-reservoir which in turn empties through its very much 

 constricted continuation into the oviduct to the left of the beginning 

 of the ovary (Fig. 4). From this point the oviduct takes a compara- 

 tively wide curve posteriorly and to the left, and then passes forward to 

 expand dorsally into the ootype which is surrounded by the little 

 differentiated, so-called shell-glands. The uterus, which begins at 



