Sl'UDIES OX THE ECTOPAKASITIC TREMATODES OF JAPAX. ^l 



pnrt of its interior was occupied by one or more clear vacuoles. The 

 nucleus, ^vliich enclosed a sing-le nucleolus, sometimes occupied a 

 central ptxsition. l)ut usually lay more or less towards the periphery of 

 the cell ; and in most cases was surrounded hy a mass of graindar cyto- 

 plasm, which was stained in ha.ematoxylin more deeply than tlie nucleus 

 itself. From this central mass the cytoplasm radi:itefl. in most cases, 

 in the form of a few threads towards the cell-wadl (PI. XXI, figs. 2 

 & o). Each cell is prolonged at (me of its corners into a long duct ; 

 and the ducts of a single group, after proceeding together for a sh(3rt 

 distance towards the lateral border, iire divided into two bundles, 

 which diverge fr(jm each other, and again unite just before opening 

 on the dorsal surf ice of the body, close to its latend margin. 



From the above descri])tion, the glan(bilar nature of these cells is, 

 I l^elieve, beyond doubt ; and comparing them with the cells of the 

 submaxillary glands'^ of the mammalia, there is such a similarity 

 between the two that it is perhaps allowal)le to conclude that these 

 unicellular glands secrete mucin and help to attach tlie body of the 

 parasite more securely to its host. 



The opening of the gland above described is armed Avith a 

 chitinous piece, Avhich is represented in surface view in fig. 3, Fl. XX, 

 and in section in its natural position in fig. o, PI. XXI f)r T. sinvd- 

 tum. and in fig. 5, PI. XXV, for T. hipamsiticum. In T. rotiunJum 

 similar chitinous pieces (PI. XXIV, fig. 7) are arranged in transverse 

 rows along the lateral margin of the body just as in Tr. mohr' ; a 

 single row consisting of f(3ur or five pieces in the middle pc^rtion of 

 the body, but of only one or two towards the ends. In this species. 



1). Landois. — Lehrlmch der Pliysiologie des Menschen. G. Aufl. p. 268-270. 



2). Pivrona e Pera<^ia. — Res lio-usticae, VIII. Di alcuni trematodi ectoparassiti di pesci 

 mariui. Xota pi'eventiva. Annali del Museo Civieo di Storia Xaturale di Genova. Ser. 2, vol 

 VII. p. 7U. 



