^38 s. GOTO. 



T. xincinntiim^ was clessribecl by Mon ti cell i '">; and finally in 1891 three species 

 were added to the genus, two [T. interrejituin and T. Lccinsenii) by Mon tic ell i-) and 

 one {T. histinphoyi) by J e f f r e y B e 1 p). 



The emended generic diagnosis of D losing^) is as follows : " Corpus saborbicu- 

 lare v. oblongum, planum v. depressum. Caput discretum, acetabulis duobus margin- 

 alibus V. jnxtapositis subcircularibus. Os inter acetabula subterminale. Acetabulum 

 corporis radiatum ventrale inferum, sessile, disciforme explanatum, intus septemradi- 

 atum, disco centrali minore. Androgyna ; aperturae genitales approximatae, 

 feminea infra os, mascula in sinistro corporis latere, pene filiformi. Porus ex- 



crctorius Tractus intestinalis bicruris, coecus. Ovipara. — Piscium marinorum 



ectoparasita." Following closely Braun and S t .- Pi e m y I give the generic diag- 

 nosis as follows : 



Body circulîir to elongated -oval, much flattened; with 

 two circular or elliptical anterior sucker.s at the anterior 

 end of the body on either side of the subterminal mouth, 

 and a single circular sessile sucker at the posterior 

 extremity. l^^sterior sucker provided witli a mar- 

 ginal membrane, with its internal surface divided by 

 means of a certain numl)er of radial septa and the bars 

 connecting them, into a central polygonal area and 

 a certain number of peri])]ieral areas; generally car- 

 rying hooks (mostly one pair). Uterus opening into 

 tlie genital atrium or independently of it directly to the 

 exterior. Genital opening or openings ventral, on the 

 left side of the body near the anterior sucker. With a 

 vagina opening ventrally on the left side of the body, 



1). Mouticelli— Tristomum unciuatum, u. sp. Boll. d. Soc. d. Xat. in Xapoli. An. Ill, fasc. 

 II. 1889. pp. 117-119. With one plate. 



2). Monticelli— Di alcuni organi di tatto uei Tristomidi : Contributo al. Stud. d. Trem. 

 uionog., parte I. Boll. d. Soc. d. Xat. in Napoli. Ser. I., aun. 5., vol. 5, 1891. p. 122, 

 Notes III & IV. 



3). Jeffrey Bell — Description of a New Species of Tristomum from llistiopliorus lireviros- 

 tris. Annals & Mag. of Nat. Hist., vol. VII, Gth. ser., 1891. pp. 531-535. 



4). Dicsing — Revision d. Myzhelminthcn, p. 365. 



