THE ANATOMY OF SCALTBREGMA INFLATUM. 277 



Glycerida3. In this family tlie pavapodium is not so obviously 

 biramous as in many others^ and he considers the whole 

 parapodium of the Glycerids is i-eally a neuropodium (the 

 notopodium being absent) equivalent to that oE Capitellids. 

 In this case the dorsal cirrus present on the parapodium of 

 Glycerids would occupy a position corresponding- to that of 

 the sense organ on the neuropodium of Capitellids. But, in 

 my opinion, the evideuce afforded by the study of the com- 

 parative morphology of the parapodia of Glycera and other 

 Polychfetes is against this argument and the conclusions 

 drawn from it by Eisig. 



The parapodia of several of the Glycerida3 are, at first 

 sight, single outgrowths, in some species the division into 

 two being only feebly marked. Each parapodium is, how- 

 ever, essentially biramous, as is shown by (I) the bifid tip of 

 the parapodium ; (2) the set« are implanted in it in two more 

 or less distinct divergent bundles. These points may be at 

 once verified by reference to the figures of parapodia of 

 several species of Glycera which Eisig has collected and 

 placed on the last plate of his monograph (see Taf. xxxvii, and 

 note especially G. capitata, fig. o1 ). The chief differences 

 between the parapodia of the various species of Glycera 

 are traceable to the varying amount of compression and 

 approximation of the parts of the parapodium. In some 

 cases tlie two rami are so closely approximated that the 

 mouths of the two setal sacs are almost confluent, but even in 

 these cases, on tracing the setae to their inner ends, it is 

 usually seen that they fall into two distinct and separate 

 groups — a notopodial and a neuropodial. There are usually 

 two acicula in each parapodium, one in the dorsal and the 

 other in the ventral ramus. These acicula are points of 

 insertion of the muscles which move the parapodium and 

 setee, and the presence of two indicates the essentially bifid 

 chai'acter of the parapodium by pointing to the fact that 

 there are two sets of muscles for moving the setje, one for 

 each bundle (see Mcintosh, 1885, pi. xlii, figs. 5, 6, 8, 10). 

 It is, therefore, most probable that the parapodium of the 



