BY WILLIAM A. HASWELL. 345 



elements remind one of the structures called " pigmented lymph- 

 glands" by Eduard Meyer,* found on the branchial vessels of 

 Terebellidae and Cirratulidae, and probably are of a similar 

 character. 



The epithelium covering the branchise is peculiarly modified in 

 Coj)pingeria, the cells as seen in sections having straight sharply- 

 defined lateral borders, as if they had acquired a stiff and rigid 

 character ; as there is no internal supporting layer, it is likely 

 that this is actually the case, and that the ciliated epithelium acts 

 to some extent as a supporting structure. 



Considerable confusion has existed regarding the relations of 

 an unpaired gland situated in the dorsal region of the anterior 

 part of the body ; it has been noticed and described by various 

 observers, but by nearly all its position has been incorrectly 

 interpreted. 



The structure in question seems to be represented in Costa's 

 figures, though it is neither referred to in the text nor in the 

 explanation of the plates. It does not seem to have been noticed 

 by Dujardin, by Quatrefages, or by Leuckart. 



ClaparedHf states that it had been observed by Delle Chiaje in 

 Stylarioides and regarded by him as a ccecum of the alimentary 

 canal. Claparede describes it as a ccecal tube of an intense black 

 colour, sometimes inclined to green, extending backwards as far as 

 the stomach, to which it adheres by its blind posterior extremity. 

 It appears to open in front on the dorsal wall of the buccal cavity. 

 It is formed of two layers — an outer, very thick, colourless, 

 muscular, and rich in vascular plexuses, the inner, an epithelium 

 of intense blackness — the cells being loaded with dark granules. 

 The functions of the gland he looks upon as entirely problematical. 



In his account of Siphonostoma^diplocha'itos the same author 

 remarks (p. 370) that Max Miiller, following Costa, had fallen 

 into a grave error in describing this structure as a large blind 

 vessel. 



* "Studien uber den Korperbau der Anneliden." 'Mittheil. a. d. Zool. 

 Stat, zu Neapel,' vh\, p. 645 (1887). 



tL.c.p. 362. 



