1901.] NATUKAL SCIENCii;S OF PHlLADELt-HlA. 721 



einen einfachen Auswuchs der Korperwaud darstellt, uud wie 

 diese mit Flimmerhaaren bedeckt erscheiut. " 



M'Intosh (1869) desci'ibes the following structure: " The pos- 

 terior end of the body in Micrura {Stylus) requires special mention, 

 since there is superadded a peculiar elongated and contractile style. 

 This appendage seems to be formed by a prolongation of the cuta- 

 neous and part of the muscular (longitudinal and circular) textures 

 of fhe body wall of the animal. The entire organ in contraction 

 has a granular appearance, the coarsest granules and occasionally 

 a few circular masses of brownish pigment, being at the tip. 

 Within these coats is a circular chamber, which undergoes various 

 alterations in size, and contains a transparent fluid. This cavity 

 is not connected with the digestive tract, which opens by a termi- 

 nal pore at the base of the process, nor can proboscidian discs be 



seen therein its connection with the circulatory [system] 



appears most probable." 



M'Intosh (1874) says that the genus Micrura has " a soft fili- 

 form caudal process, capable of attachment." He further alludes 

 to " a pale caudal filament" and " a slender styliform process 

 attached to the tail " which " can be elongated to an extreme 

 degree. ' ' 



Hubrecht (1887) used the term " caudal papilla " throughout 

 his description of the caudicle. 



Verrill (1893), in defining the genw?, Micrura, says: "Poste- 

 rior end of the body provided with a median slender cirrus, above 

 the anus. This genus, as here defined, differs from Lineus in little 

 else than the presence of a well-marked contractile anal cirrus, 

 which may often be distinguished even in alcoholic specimens. 

 From Cerebratuhis, which also has the anal cirrus, it differs in the 

 form and muscular structure of the body posteriorly. " In other 

 parts of this work the terms " anal papilla," " caudal papilla" 

 and " caudal filament " are indiscriminately used. 



Verrill (1895) employs the expression " caudal cirrus." 



Burger (1895) describes " ein diinnes 5-15 mm. langes, meist 

 borstenartig starres, weissliches Anhiingsel," which he terms " das 

 Schwanzchen." On p, 24, in reviewing the work of Dalyell, 

 Burger employs another term, saying that Dalyell " den Appendix 

 beobachtet und gut gezeichnet hat." 

 46 



