184 TAPEWORMS OF HAKES AXD RABBITS STILES. 



2. The second species, C. perplexa, is directly intermediate between 

 the first and third, "but I am unable to find connecting links between it 

 and the other forms. The cirrus pouch is about two thirds as large as 

 that of C. pectinata and somewhat more distinct than that of C. rarl- 

 abilis; the testicles are arranged in two triangles and extend laterally 

 beyond the ovaries to the lateral canals. In general configuration of 

 the body it resembles C. pectinata very closely, but is much shorter. 



3. C. variabilis represents the last form of the series, presenting a 

 cirrus pouch slightly smaller than that of G.perplcxa and testicles in a 

 quadrangle which is confined entirely to the space between the ovaries. 

 It occurs in three different forms as follows: 



(a) C. variabilis found in Lepus sylvaticus with characters described 

 below, p. 192 7 measuring up to 10 mm. broad, the segments always much 

 broader than long. 



(b) C. variabilis angusta differs from C. variabilis only in point of size; 

 it measures only 2 mm. broad and the segments are about three times 

 as broad as long. This form I have never found with ova, and it may 

 be a case of arrested development. Those authors who take external 

 form as a specific character would be obliged to give this parasite spe 

 cific rank, but I am unable to admit this view. This variety is found 

 in Lepus sylvaticus. 



(c) C. variabilis imbricata is the third variety, and is one due proba- 

 bly entirely to host influence. It is found in Lepus palustris in Florida. 

 The differences between this form and the type are but very slight ; the 

 posterior margins are more scalloped, the segments more imbricate, and 

 the cirrus pouch slightly more distinct. 



CITTOT^ENIA PECTINATA (Goeze, 1782 partim, Riehm, 1881), Stiles & Has- 



sall, 1896. 



(Plate XVI, figs. 1-2; Plate XVII, figs. 1-2.) 



?1781, Tcenia acutissima, PALLAS, Neue nord. Beytrage, I, pp. 75-81, pi. in, fig. 25. 



1<S^, T. pectinata, GOEZE, Versuch einer Naturgeschichte d. Eingeweidew., pp. 363- 

 368, pi. xxvn, figs. 7-13. 



?1800, Alyselminthus pectinatus (GOEZE, 1782), ZEDER, Erster Xachtrag zur Naturg. 

 d. Eiugeweidewurrner, pp. 246-249. 



?1803, Halysis pectinata (GoEZE, 1782), ZEDER, Anleitung zur Naturg. d. Einge- 

 weidewiirmer, p. 332. 



1810, Tamia leporiua* RUDOLPHI (in synonymy), Ent. Hist. Nat., II, Pt. 2, p. 82. 



1881, Dipylidium pectinaliim (GOEZE, 1782 partim), KIEHM, Zeitschr. f. d. ues. 

 Naturwiss., 3 ser., VI, p. 200; pp. 575-583, pi. v, tigs. 4, 14; vi. iigs 4, 7. 



1891, Moniezia pectinata (GOEZE, 1782 partim, Riehm, 1881), R. BLAXCHARD, ^lom. 

 Soc. zoel. France, IV, pp. 187, 445, 450-452, 457-460, figs. 26-30. 



1893, Ctenotcenia pectinata (GoEZE, 1782 partim, Riehm, 1881), RAILLIET, Traite de 

 Zool. uicd. et agric., I, pp. 278-279. 



1896, Cittotccnia pectinata (GOEZE, 1782 partim, RIEHM, 1881), STILES & HASSALL, Vet- 

 erinary Magazine, III, p. 407. 



'Blaiichard (1891A, p. 457) has already shown that Limbonrg (1766) did not use 

 " Twnia leporina" as a specific name; the name therefore dates from Rudolphi, 1810. 



