736 OBSERVATIONS OS SOME AUSTRALIAN POLYCH^TA, 



There is a circlet of about twenty compressed papillre in the 

 oesophagus. The tooth is hyaline, tviangalar, acutely pointed. 

 The part of the lining membrane external to the papillae is light 

 red in the living state, that of the part following light pink. The 

 cuticle of the oesophagus is extremely thick and hard, the epithe- 

 lium composed of very narrow, fibre-like cells. The structure of the 

 following division of the alimentary canal will be fully described 

 by me elsewhere (1). It has usually been regarded as a glandular 

 organ (Driisenmagen, proventricule, stomach), but is really much 

 more properly called a gizzard. It has a compai-atively thin 

 cuticle, like that of the outer surface, and an epithelium consisting 

 of non-ciliated colummar cells, with conical and spindle-like 

 "cellules de remplacement" at the base. The remainder of the 

 thick wall of the organ is composed of muscular tissue — an 

 external and an internal layer of the ordinary non-striated fibres 

 arranged circularly and longitudinally, and a middle layer, which 

 is by far the thickest, composed of striated fibres arranged in a 

 radiating manner. There is, in addition, a set of non-striped 

 fibres, which do not form a complete layer, but are disposed as a 

 series of rings between the outer ends of the striated fibres. The 

 wall of the organ presents on either side a raphe, where the 

 striated fibres are absent and the layers of non-striated fibres 

 blend. The striated fibres present a nucleated protoplasmic core, 

 and the striations in their substance are of a very marked 

 character. What are ordinarily described as the transverse rows 

 , of glands, are these rows of columns of striated muscle. They have 

 been described and figured as glands by many observer.s, 

 Claparede (2), Langerhans (3), and Ehlers (4) among the number; 

 their muscular character, was observed by Eisig. (5), who, how- 

 ■ever, overlooked the striations. 



(1) I have previously given the present species the temporary designation 

 of Syllis a. 



(2) " Ann(ilides Ch6topodes du Golfe de. Naples." 



(3) " Zur Wurmfauua von Madeira" and " Canarische AnneUden." 



(4) " Die Borstenwurmer." 



(5) "Ueber das Vorkommen eines Schwimmblasenahnlichen Organ bei 

 Anneliden." Mittheil. aus der Zool. Stat, zu Neapel, II. Band. 



