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PROCEEDINGS OF THE NATIONAL MUSEUM 



Ostracod associates include Dn. ardis at station 25; Dn. ileata at 

 all stations except 70; Dt. daphnioides at 70, 72, 73, 75, 79, 81; and 

 P. phyma at 3, 5, 24, and 64. 



Branchiobdellid associates include A. koronaeus at stations 18, 19, 

 72; A. legaeus at 81; B. illuminatus at 5, 19, 76, 86, 97; C. branchiophila 

 at 15, 18, 24, 43, 58, 63, 65-67, 72, 73, 75, 79, 81, 86, 97, 104; C.jallax 

 at 3, 5, 15, 18, 24, 43, 58, 61, 63, 65-67, 70, 72, 75, 79, 81, 86, 95, 97; 

 C. heterognatha at 3-5, 24, 61, 63-67, 70, 72, 79, 81, 86, 97, 105; 

 C. holostoma at 18, 19, 25; C. ingens at 5, 15, 18, 58, 61, 64, 67, 70, 

 72, 73, 75, 79, 81, 86, 95, 97, 104; C. philadelphica at 3, 5, 19, 24, 25, 

 66, 74, 76; and Xg. instabilins at 3-5, 24, 61, 64, 86, 95, and 97. 



Figure 20. — Pterodrilus alcicornus, lateral view. 



Genus Xironodrilus Ellis, 1918 



Diagnosis. — Body depressed, widening gradually from segment I 

 to segment VII; deferent ducts entering ental end of spermiducal 

 gland; prostate absent; bursa spherical. 



Xironodrilus formosus Ellis 



Figures 21a-d 

 Xironodrilus formosus Ellis, 1918, p. 49. 



Diagnosis. — Dental formula 4/3 to 6/5, teeth subequal in size 

 with lateral teeth somewhat shorter than median ones; spermathecal 

 duct distinct, bulb of spermatheca globose or cylindrical; spermiducal 

 gland simple U-shaped tube, less than twice diameter of vasa defer- 

 entia; ejaculatory duct absent. 



