BY T. HARVEY JOHNSTON AND 0. W. TIEGS. 117 



the region of the mouth Avhich must be a fairly labile organ. The pharynx 

 which lies close behind the mouth is relatively very large, measuring nearly .1 

 mm. in length. Thei'e is a short oesophag-us. No details of the intestine could 

 be made out in the material available. 



Immediately in front of the pharynx are four eyes, the posterior two being 

 larger and situated further apart. 



The genitalia are rather difficult to observe on account of the closeness with 

 which they are massed together in this short animal. The ovary is situated in 

 the midline slightly behind the middle of the animal. It is bent once upon 

 itself in the transverse direction and then opens by a short oviduct into the 

 uterus. The latter is a long narrow tube, apparently Uned distally with a thin 

 layer of chitin. It opens close beside the pharynx, and when an egg is present 

 is seen to be considerably distended in this region where the shell-glands lie. A 

 very short vagina is present, opening on the mid-ventral region by a very dis- 

 tinct aperture. What appears to be a very large receptaculum seminis is to be 

 .seen in close connection with the vagina. 



The vitelline system is very well developed and obscures all structures be- 

 neath it. The transverse yolk-ducts pass inward towards the female ducts im- 

 mediately in front of the ovary. The yolk-glands extend from the region of the 

 pharynx right to the posterior end of the body, where they are especially 

 abundant. 



The testis is fairly large, lying beside and close behind the ovary. The vas 

 deferens passes forward on the left side of the body, to open into a very 

 ]irominent vesicula seminalis close behind the pharynx. The penis seems to be 

 a fairly large, though not very distinct structure, lying close to the vesicula, but 

 its exact structure could not be made out. 



From the gills of a common stingray, Vrolophiis testacetis Mull. & Henlc 

 from Sydney. 



24. T R ] N c H u s MacCallum, 1916. 



"The mouth large and sub-terminal, much like an ordinary sucker; genital 

 pore central; cirrus chitinous; single testicle posterior to ovary; a relatively 

 large sucker disc with one large loculus in the centre and three small marginal 

 ones. There are also on the disc three hooks, one large one terminating in two 

 points and also two smaller ones" (MacCallum). To which may be added: — 

 pharynx remarkably small; ovary very large and bent in a semicircle; vagina ap- 

 parently absent. 



Type and only known species, T. da,sijhatis MacCallum, 1916, from the 

 gills of Basyhatus pastinacus at Wood's Hole, Massachusetts. 



Subfamily II. CALICOTYLINAE Monticelli, 1903. 



Bather large robust Monocotylidae, much broader behind than in front ; 

 the disc very much narrower than the body and divided into a number of suckers. 

 Large hooks present on disc. ■ Vagina double. Testis broken up into numerous 

 follicles. Cirrus simple. 



Calicotyle Dies, is the only genus as yet known belonging to this subfamily. 



25. Calicotyle Diesing, 1850. 



Disc divided by seven radii into as many marginal suckers; a small central 

 sucker also present on disc. Minor hooks absent, but two large powerful hooks 

 present. Testis elongated transversely and broken up into numerous follicles. 



