278 J. H. ASHWORTH. 



GlyceridsD is truly bii'amous, each ramus bearing a group of 

 setae. Moreover, the notopodium and neuropodium of 

 Glycerids are equivalent to the correspondingly named 

 structures in other Polychsetes, the sole difference being that 

 in the former the typical parts of the parapodium have 

 become more closely approximated and merged into one 

 another than is usual. 



This may be further emphasised by a comparison of the 

 parapodia of Grlycera and Scalibregma. There is no 

 difficulty in homologising the parts common to both. The 

 parapodium of each of these genera bears two bristle bundles 

 — a notopodial and a neuropodial — and also a dorsal and 

 ventral cirrus. In addition there is in each parapodium of 

 Scalibregma a structure not represented in Glycerids, — the 

 lateral sense organ, which is situated between the two rami 

 in a position corresponding to that of the " Seitenorgane " of 

 the Oapitellid parapodium, 



Eisig's assumption that the whole parapodium of Glycerids 

 is equivalent to the neuropodium of Capitellids does not 

 appear therefore to hold good. The facts cited above go far 

 towards proving that the Glycerid pai-apodium contains a 

 notopodium and a neuropodium morphologically equivalent 

 to, but less distinct than, those of Capitellids, If this be 

 admitted, then the assumed homology of the " Seitenorgane " 

 of Capitellids with the dorsal cirrus of Glycerids falls, as the 

 two structures are not in the same morphological position, 

 and have not the same relationship to the respective rami of 

 the parapodia, for the dorsal cirrus is an appendage on the 

 dorsal side of the notopodium, whereas Eisig contends 

 that the " Seitenorgan " represents the cirrus on the dorsal 

 side of the neuropodium. 



After a careful examination of the lateral sense organs of 

 Scalibregma, I have come to the conclusion that they are 

 not very inbimately related to either ramus of the para- 

 podium, they occupy a position between the two rami. 

 Moreover, a study of the excellent figures which Eisig has 

 given of these organs in the CapitellidjB shows that they are 



