BY S. J. JOHNSTON. 737 



intestinal limbs, receiving numerous tributaries from the follicles 

 as it passes (Fig. 9). The anterior and posterior parts of these 

 ducts meet at tlie level of the anterior edge of the anterior testis, 

 and, from the point of junction on each side, a transverse duct 

 proceeds to meet its fellow of the other side, in the mass of the 

 shell-gland. 



The elliptical eggs are light-j'ellow in colour, very large(0-l 34 x 

 0079 mm.), and comparatively few in number. 



Mehlisia oknithorhynchi mihi. 



(Figs. 4 and 11.) 



Parasitic in the duodenum of the platypus, Ornithorhynchus 

 anatinus. 



Diagnosis. — Elongated worms, tapering somewhat, but rounded 

 off at each end. Integument spiny, spines larger than in M. acumi- 

 nata. Suckers large, near together; ratio of oral to ventral, 2:3. 

 Pr»pharynx, pharynx, no oesophagus, simple intestinal limbs ex- 

 tending to the posterior end. Excretory system of vessels and 

 sinuses as in the genus. Copulatory organs present. Testes 

 elongated, lobulated, obliquely placed in the middle line, one behind 

 the other. Ovary, uterus, shell-gland, Laurer's canal and reeepta- 

 culum seminis as in M. acuminata. Vitelline glands as in M. acu- 

 minata in regard to their extent, but consisting of larger follicles. 

 Eggs 0-13 X 0-069 mm., few in number. 



Type-specimen in the Australian Museum, No. W. 354. 



I have already published an account of this species, in the Pro- 

 ceedings of this Society (7), where a figure of the worm is given. 

 In that figure, the structures marked d.s.g., should be the Laurer's 

 canal. Fig. 4 in this paper is a corrected presentment of the 

 female organs. The general anatomy, and especially the excretory 

 system, are very similar to the descriptions given for M. acumi- 

 nata. It differs from that species principally in the shape of the 

 body, in its smaller size, in the larger size of its spines, in tlie 

 I'atio of the suckers, in the oblique position and more elongated 

 form of the testes, and in the larger and less numerous follicles of 

 the yolk-glands. 



