358 LEWIS HENRY (iOUGH. 



are. Next to the subcuticula one also finds two sets of 

 muscles ; the outer is also composed of circular, concentric 

 muscles, the inner of radial fibres. These two sets are witli- 

 out doubt subcuticular muscles; the " Sommer-Laudois" cells 

 mentioned above stand in contact with them. Between the 

 cuticula and delimiting membrane are the radial fibres ; in 

 the middle of the thickness of the sucker there are other 

 muscles, running at right angles to the radial fibres, whose 

 course is possibly circular. These two last sets are without 

 doubt parenchyma muscles. 



Around the margin of the opening of the suckers the sub- 

 cuticular circular muscles are much developed, forming a 

 kind of sphincter. 



It is worthy of remark that the subcuticular muscles of the 

 suckers are much more developed in Avitellina and Ano- 

 plocephala than in Taenia and Dipylidium. 



The Excretory System. Figs. 5, G, 30-87. 



The excretory system consists of the usual two pairs of 

 longitudinal canals, the secondary transverse commissures, 

 and of the flame cells and their capillaries. 



In the strobila the ventral canal is enormously developed; 

 it lies lateral to the dorsal canal, whose lumen almost 

 atrophies in the posterior portion of the strobila. 



Transverse commissures connect the ventral canals ; they 

 are not very readily observed in Avitellina centripunc- 

 tata (Rivolta), but are wide and conspicuous in Stilesia 

 hepatica, WolfShiigel, Stilesia vittata, Railliet, and 

 Stilesia globipunctata (Rivolta), where they form a more 

 or less complicated network at the posterior end of each 

 segment. 



The flame cells are very frequent in the medullary zone of 

 Avitellina centrip unctata (Rivolta), but extremely rare 

 exterior to the transverse muscle. This is worth notice, as in 

 other cestodes (Tt«nia serrata, Goeze, Dipylidium 

 caninum [L.], and Ligula [fide Blochmann]) they seem 

 to be very fre([uent among the subcuticular cells. 



