6Y T. HARVEY JOHNSTON AN1> 0. W. TIEGS. 223 



tudinal muscle layer, continuous with the corresponding muscle 

 layers of the body wall. The oblique muscle layer is absent. 



Male. — The male is an extremely degenerate, elongated organ- 

 ism which in transverse section may appear almost circular or 

 nearly semi-circular. It is about 06 mm. in length and 012 to 

 016 mm. in maximum breadth. The anterior end appears more 

 or less spherical, this portion being followed by a somewhat con- 

 stricted region, the remainder of the worm being cylindrical, 

 with a diameter approximately equal to that of the anterior 

 portion. There are no ventral setoe. The epidermis on the 

 anterior portion of the male is cubical; but posteriorly its cells 

 are very elongated to form a prominent structure. In the mid- 

 region of the body the cells are of an intermediate character. 



Below the epidermis lies a thick mass of dermis (" trabecular 

 layer " of Ikeda; " parenchyma" of Spengel) of a rather loose 

 texture, surrounding the ccelome. It contains abundant lacunae. 

 In the posterior portion of the organism there is a definite system 

 of longitudinal muscle fibres (subperitoneal musculature of Ikeda, 

 1907) lying in the dermis, close to the ccelome. They can be 

 best distinguished in longitudinal section. In immature males 

 the ccelome is practically obliterated, but in mature forms it is 

 well developed, and may be divided into a small but almost 

 spherical portion at the anterior end of the organism, joined by 

 a very narrow canal with an elongated but not so dilated pos- 

 terior part. No peritoneum could be detected lining the body 

 cavity except the anterior dilatation. 



The anterior portion of the ccelome lodges the sexual organs, 

 alimentary canal and nerve. The last-named is very ill-defined, 

 occurring as a slight prominence mid-ventrally, projecting into 

 the ccelome from the ventral body wall. Nothing could be made 

 out regarding its structure. It appears to be absent from the 

 posterior part of the animal. 



The alimentary canal is also extremely rudimentary, mouth 

 and anus being absent. It lies in the front portion of the 

 anterior dilatation of the ccelome, being recognisable as a short, 

 vesicular, rudimentary structure with a rather definite lumen, 

 and about 003 mm. in length. Its wall consists of comparatively 



