248 Georgina Siveet : 



{see Figs. 16 and IT). Tlier commence at various distances, 

 .034:, .06 and .18 mm. from the anterior end, and extend back- 

 wards for .09 to .129 mm., attaining a maximum Avidth of 

 .03 mm. They seem to be always uneven, both in their anterior 

 "boundary and in length on the two sides. These are presumably 

 ■comparable with the " voluminous lateral cuticular membranes ' 

 given by Ransom as characteristic of 0. auaranthura (1904, 

 p. 21) and the '' bladder-like expansion " of 0. hrerisuhulata 

 ^Ransom, 1904, p. 23). 



In the form now being described, although these structures are 

 not constant in their full development, other male specimens in 

 addition to those mentioned above sliow a tendency towards 

 the lateral expansion of the cuticle at points varying in position 

 on the head region. When these cephalic wings are largest the 

 body is ah\ ays constricted in the region over which the '' wings " 

 are present (cf. Fig. 16). 



The mouth is somewhat oval, and is surrounded by 6 small 

 oral papillae, 4 submedian and 2 lateral, and further i:)ack there 

 are also 4 sublateral papillae (Figs. 17 and 18). The 6 oral 

 papillae are extremely difficult to see from any aspect, and in 

 onlv one of these 16 specimens have I been able to view them 

 all in the one individual, and then only under the most favour- 

 able conditions, so that one is inclined to doubt the constant 

 presence of the full number. The 4 sublateral papillae are com- 

 paratively large and clear. No regular chitinous ring with 

 c-lefts, as in 0. mansoni, is present, although the large anterior 

 opening of the pharynx is sometimes partially closed over by a 

 thin indefinite and irregular cuticular membrane. 



The nerve-ring is sitiuited 220 to 300 /t from the anterior 

 end of the body (see Fig. 15 n.r.). The excretory pore is situ- 

 ated at 360 to 460 //. from the anterior end (see Fig. 15 e.p.), 

 and near the same transverse plane the small inconspicuous 

 cervical papillae may sometimes be seen. No caudal papillae 

 are present in either sex. 



The pharynx (Fig. 17) has a total length of 34 to 50 //., gene- 

 rally, however, about 45 (j.. The anterior portion, which, like 

 that of 0. mansoni, is shorter and wider and more rounded, is 

 17 to 30 /x long by 27 to 36 /x wide, the hinder more cylindrical 



