SOME POINTS IN THE ANATOMY OP POLYCH^TA. 249 



Keferstein (' Zeitschrift fur wiss. Zoologie,' Bd. xii, 1862) 

 mentions that the structure and number of the nephridia in T. 

 conchilega are the same as in T. gelatinosa, Kef. ; in both 

 cases he says there are six pairs, each organ consisting of a tube 

 bent on itself, of which one half is darker, the other lighter ; 

 the organs belong to segments 3 — 9. 



Cosmovici 1 gives an erroneous description of the organs; he 

 says there are two pairs without internal openings, which he 

 calls " organs of Bojanus," one of these situated in front of the 

 cephalic diaphragm, the other immediately behind it, each organ 

 having an external opening; and two other pairs, each of which 

 has an internal as well as an external opening, and is shaped 

 like an urn; the internal opening is large, and surrounded 

 with a circular lip. The gonad is attached to the posterior 

 part of each of these latter organs, which Cosmovici calls seg- 

 mental organs, and which he says serve as efferent genital 

 ducts. 



The species referred to by these three authors is the Nereis 

 conchilega of Pallas, Terebella conchilega of Gmelin ; 

 and this is called Lanice conchilega by Malmgren. My 

 specimens were identified from Malmgren's description, and 

 there is no doubt of their identity with the species of that author ; 

 but there is room for some uncertainty regarding the specific 

 identity of the specimens referred to by the authors I have men- 

 tioned. For instance, Cosmovici identified his species by means 

 of Quatrefages' ' Histoire des Anneles/ 1865, and there it is 

 stated that the tube of Terebella conchilega possesses no 

 hollow fringes at its mouth; these fringes are always present in 

 the tube of Lanice conchilega, Malmgren. This species is 

 distinguished by some marked characters; two of them are the 

 presence of a large vertical lobe on the third somite (second 

 branchiferous), and the coalescence of the ventral scutes usually 

 present into a continuous ventral plate. 



The fact that in Lanice conchilega the nephridia of a side 

 communicate together so as to form a longitudinal tube, has 



1 " Glandes genitales et Organes segmentates des Annelides polychet.es," 

 ' Arch, de Zool. Exp.,' t. viii, 1879-80. 



