382 



BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



Host. — Primary : Fulica atra; secondary : Probably fish, according 

 to Jaegerskiold. 



Location. — Esophagus. 



Morphology. — Hystrichis (p. 375) : Head a knob-like thickening 

 with rounded summit surrounded by a horny border, with a crown 

 of conical, straight smooth spines, 17 to 18 in each row. According 

 to Wedl T the spines disappear 3 mm. from the head end. 



Male unknown. 



Female 100 mm. long by 3 mm. wide. 



mm 



Km 



I 



W/Mf'/H 

 7/iffi/r 



tinum i 

 [nrwj: 



Figs 442-444. — 442, Hystrichis orispinus. Head end. From Jaeger- 

 skiold, 1909, after Molin. 443, Hystrichis varispinosus. a, Head 



END ; b, SPINE OF ANTERIOR CERVICAL REGION. AFTER JaEGEIRSKIOLD, 



1909. 444, Hystrichis wbdli (Linstow's material), a, Anterior 

 portion of body ; b, one of the most anterior spines, lateral view ; 



C, SAME, FRONT VIEW; (I, ONE OF THE MOST POSTERIOR SPINES; €, POSTERIOR 

 END OF BODY (X, PROBABLE PRIMORDIUM OF VAGINA). AFTER JAEGERSKIOLD, 

 1909 



Larva (found by Linstow) 24 mm. long by GOOju. wide; anus 

 terminal; head and tail ends rounded; esophagus 1/4 of body length. 

 Cuticle thick, made up of 3 layers, with transverse striations, with 

 posteriorly directed conical spines 69^. long by 29/x wide at the base, 

 very thick at head end (fig. 444 a to d), smaller and less numerous 

 posteriorly but extending to tail end of body (fig. 444e). Outer 

 cuticle about to be cast off, the head end showing new structure as 

 described by Wedl for adult. 



Life history. — Unknown; possibly similar to that of H. tricolor, 

 p. 376. 



Distribution. — Not given. 



