BY S. J. JOHNSTON. 731 



The small dark-shelled eggs (0-0254 x 0-0165 mm.) have the 

 characteristic elliptical shape, flattened on one side, and are very 

 numerous. 



Haismostomum simile, n.sp. 



Parasitic in the intestine of the bandicoot, Perameles ohesula, 

 found in the vicinity of Sydney, N.S.W. (Fig. 2). 



Diagnosis. — Small worms, oval in cross-section, rounded in front, 

 pointed behind, about 3 mm. long, by 0-5 mm. broad. Integument 

 spiny on the ventral and lateral surfaces, but smooth on the dorsal 

 surface, except at the extreme anterior end. Suckers comparatively 

 large, ratio of the oral to the ventral sucker, 3 :4. Alimentary and 

 excretory systems as in //. dastjuri. Gonads oval: anterior testis 

 smaller than posterior, fairly globular in form. Genital pore near 

 the anterior edge of the anterior testis. Cirnas and vagina well 

 developed and muscular, but cirrus-sac very poorly developed, 

 Laurer's canal present, but no receptaculum seminis. Uterus and 

 yolk-glands as inH. dasyuri. Eggs very small, 0-0-219 x 001 '29 mm. 



Type-specimen in the Australian Museum, No. W. 353. 



I have received four specimens of this worm, one from the 

 Bureau of INIicrobiology, Sydney, and three from my friend. Dr. 

 Harvey Johnston, of the University of Queensland. Two were 

 sectioned, and the others mounted whole. 



This is obviously closely related to the foregoing species, pretty 

 closely corresponding in its anatomical structure, but differing 

 from it in its much smaller size, in the relative sizes of the suckers, 

 in being less spiny, in its more weakly developed cirrus-sac, in the 

 anterior testis being smaller than the posterior, and subglobular, 

 and in the size of the eggs, which are smaller in H. simile. In the 

 latter, too, the testes are nearer the posterior end, so that there is 

 practically no tail. All four worms were about the same size, the 

 average length being 2-98 mm-, breadth 0-52 mm. The diameter 

 of the oral sucker averages 0-273 mm., that of the ventral 0-372 

 mm. The pharynx, with a diameter of 0-155 mm., is compara- 

 tively larger than in H. dasyuri. The anterior testis measures 

 0-218 mm. in average diameter, the posterior 0-272 x 0-239 mm., 

 the ovary 0-227 x 0-187 mm. 



