52 Papers from the Marine Biological Laboratory at Tortugas. 



Xystretrum papillosum gen. et sp. nov. (Figs. 107-111.) 



Neck distinct from body, cylindrical, arcuate; body suborbicular 

 with thin border and thickened, muscular ventral disc crossed by low, 

 transverse ridges. Papillar spines cover the neck and body and line the 

 cavities of the suckers. In Hfe, color of neck pink, of body yellow with 

 white margin; mouth subterminal; ventral sucker larger than oral; no 

 pharynx, no esophagus; intestinal rami in the neck with irregular out- 

 hne extending to posterior edge of disk. The intestines follow the lateral 

 borders of the disk but being obscured by the uterus it could not be deter- 

 mined whether they unite at the posterior end or not. Genital aperture 

 median, ventral, near the posterior border of the oral sucker; cirrus short 

 and smooth; cirrus-pouch between the intestinal rami in front of the 

 ventral sucker, inclosing the convoluted seminal vesicle; prostate not 

 distinct. Testes 2, nearly transverse, deeply lobed, situated a short 

 distance behind the ventral sucker. Ovary indistinctly lobed, close to 

 anterior border of right testis. Vitelline glands between the left testis 

 and ovary at caudal border of ventral sucker, made up of about 4 very 

 irregular and somewhat lobed tubular masses. The uterus is a very 

 slender tube lying in intricate folds and filHng all the body behind and 

 lateral to the testes except the thin border which lies outside the ventral 

 disk. The metraterm hes on the right side of the seminal vesicle and ap- 

 pears to enter the cirrus to open with it by a common duct; ova small 

 and presenting some variety in size. 



Dimensions in balsam: Neck, length 1.40, breadth at anterior end 

 0.50, at base 0.73; body, length 2.10, breadth 2.17; oral sucker, length 

 0.42, breadth 0.45; ventral sucker, length 0.62, breadth 0.63; diameter 

 of ventral disc 1.58; distance between ridges of disk 0.04; ova 0.030 by 

 0.015 and 0.040 by 0.020. 



Host, Lactophrys triqueter: July 8, 1908, i fish, i distome. 



Hysterolecitha rosea gen. et sp. nov. (Figs. 112-117.) 



Etymology: ufTTs/xxi, last, posterior; /^/cj^c^, yolk. 



Body smooth, cylindrical, red in hfe, greatest diameter at ventral 

 sucker, which is situated near the anterior third of the length, thence 

 tapering to each end; mouth subterminal, oral sucker and pharynx each 

 nearly globular and contiguous; ventral sucker nearly three times the 

 diameter of oral sucker; esophagus about as long as the pharynx. The 

 intestinal rami extend nearly to the posterior end. Reproductive aper- 

 ture on the midventral line at the junction of the intestinal rami.' Cirrus 

 short; prostate represented apparently only by a small cluster of cells 

 near the reproductive aperture. The seminal vesicle is an elongated 

 tube, somewhat convoluted and lying beside the metraterm in the neck. 

 Testes 2, near together, one following the other a little diagonally, not 

 far back of the caudal border of the ventral sucker. The ovary is situated 

 towards the posterior end, at about the posterior fourth or fifth, sub- 

 globular; yolk-glands at caudal border of ovary, 2, the left deeply lobed, 

 the right less deeply lobed. There is a seminal receptacle which is tubular 

 and situated behind the yolk-glands. The shell-gland is dorsal to the 



