397] AN0PL0CEPHAL1DJE—D0UTHITT 47 



complete 110 to 140 proglottids; Stiles' material measured up to 400/* 

 long. Eggs begin to pass into the uterus in the 45th proglottid in one 

 of my own specimens. My measurements of the heads of the two 

 specimens show diameters at the base of 700 and 745/* respectively but 

 confirm Lyman's measurements for the specimens he studied. There 

 seems no reason to doubt Stiles' figures which give the diameter of the 

 head as 250/* or less. These different figures show little reliance is to 

 be placed upon these characters. 



In certain features the American representatives of this species 

 are different from the European and should be designated as a distinct 

 variety to avoid confusion. The following is the characterization. 



Cittotaenia pectinata: Strobila up to 400 mm. long. Sexual ma- 

 turity about 30 mm. from the anterior end. Testes about 150, extending 

 uniformly across the distal end of the proglottid, from excretory duct 

 to excretory duct. Hosts Lepus timidus and Lepus variabilis. Known 

 distribution, Germany and France. 



Cittotaenia pectinata americana: Strobila 44 to 71 mm. long. 

 Number of proglottids, 85 to 140. Sexual maturity reached in about 

 the 45th proglottid, about 10 mm. from the anterior end. Testes 100 

 to 125, extending from excretory duct to excretory duct in the distal 

 end of the proglottid, sometimes nearly absent from the median part 

 of the field. Host, Lepus californicus melanotus. Known distribution, 

 eastern Kansas and Nebraska, U. S. A. 



Of Cittotaenia perplexa, I have studied U. S. National Museum 

 cestode No. 1110, which is one of the specimens upon which Stiles 

 (1896) based his original description and which was designated by 

 him a cotype. Permission was given to dismount and section the speci- 

 men. Inasmuch as it had been mounted in balsam for 18 years, this 

 was obviously a difficult task to accomplish; but by careful work two 

 series of sections have been made, which, while by no means suited for 

 careful study, are sufficient to show that all the differences supposed 

 to exist between this cestode and C. mosaica (Hall, 1908) are due to 

 errors or incorrect conclusions as to the former. These points will be 

 taken up one at a time. 



The cirrus pouch Stiles (1896) records as being 288 to 320/* long 

 in C. perplexa. Eighteen pouches I measured, however, were all 530/* 

 long. Hall found the pouch in C. mosaica to be 475 to 640/* long, with 

 an average length of 550/*. There is therefore no difference in this 

 regard. In position and form the cirrus pouch and vagina are iden- 

 tical with Hall's descriptions. The specimen at hand is not suited for 

 histological study and comparison. According to Stiles' description 

 the testes of C. perplexa are absent from the median part of the pro- 



