NO. 1105. PROCEEDINGS OF THE NATIONAL MUSEUM. 189 



about 10 mm. broad by 1.5 mm. long. The anlagen of the genital organs 

 appear very early; the female anlagen are found near the longitudinal 

 canals immediately back of the head; testicles appear about (> mm. 

 back of the head; genital pores double, in posterior half of margin. 

 Male organs: The testicles are about O.G4 mm. iu diameter; they are 

 numerous, about 150 in number, confined to distal half of segment, 

 posterior to uterus, and extend across the entire median field passing 

 the ovary on each side to the longitudinal canals; cirrus pouch unusu- 

 ally large, attaining 1 mm. in length, extending some distance median 

 of the longitudinal canals. Female organs: Ovary, shell gland, und 

 vitellogene gland situated some distance median of the ventral canal, 

 about 1 mm. or more from the lateral margin; a common transverse 

 uterus to both ovaries; it passes the ovary ventrally, is generally larger 

 in its lateral portions than in its median portion, and increases its 

 volume by proximal and distal branches. Excretory system: Dorsal 

 canal not observed; ventral canal median of nerve; transverse canals 

 connected by secondary longitudinal canals. Longitudinal nerves close 

 to lateral margin. Cirrus pouch, vagina, and uterus pass from median 

 field into lateral field dorsally of nerve and longitudinal canals. Cirrus 

 pouch dorsal of vagina on both sides of the segment. Ova globular 56 to 

 84 //. in diameter; bulb of pyriform body 14 to 1C //; horns long, curved. 



Hosts. Common European hare (Lepus timidus) by Goeze, liiehm, 

 von Linstow, and Stiles; Mountain hare (L. variabilis) by E. Blanch- 

 ard. Development unknown. 



Types. Original types 1 Cotypes of Eiehm in the collection of 

 Leuckart; No. 1411, U.S.N.M. Typical specimens in collection of 

 Blanchard; collection of Moniez; collection of Stiles (Xos. 116, 1234, 

 1238, U.S.N.M.). 



Geographical distribution. Europe: Germany (Saxony by Eiehm and 

 Stiles; ? by Goeze); France (Biiancon by It. Blanchard; ? Lille by 

 Moniez). 



CITTOT^NIA PERPLEXA (Stiles, 1895), Stiles & Hassall, 1896. 

 (Plate XVIII, figs. 1-3.) 



1895, Ctenotcsnia perplexa, STILES, Veterinary Magazine, II, June, p. 345. Aug. 28, 1896. 



1896, Citlotmiia perplexa ( STILES, 1895), STILES & HASSALL, Veterinary Magazine, II I, 



p. 407. 



The specific name perplexa was proposed because it was so difficult 

 to decide what to do with the form under discussion. Some half a 

 dozen specimens were collected by Hassall from Lepus sylvaticus in 

 Bowie, Maryland. They are all contracted and measure up to 57 mm. 

 long by 10 mm. broad. 



The parasite resembles C. pectinata in general form in the early 

 appearance of the genital anlagen and in the fact that the testicles 

 extend beyond the ovaries to the lateral canals. It differs from C. pec- 

 tinata radically in the size of its cirrus pouch and vagina, and in the 



