36 W. C. Minor upon Fission in some Annelids. 
esate rected Frey and Leuckart and others, seem to 
complete knowledge than we as yet possess of 
io waynes 4 in the fresh water group. 
may here remark that the European species chiefly studied 
hitherto, Stylaria proboscidea, has not come under my observation, 
nor am I aware that it has been found in America. Four spe- 
cies of Naids common in this vicinity, Sty/aria (Pristina) longt- 
seta, Nats rivulosa, and Dero limosa, found in fresh water, and a 
marine Enchytreus, E. triventralopectinatus, have been the prin- 
cipal subjects of my investigation. In regard to the first of 
these, it may be ge aaete agi our species is identical with 
that described by Ehrenberg, (Symbole Physice,) as Pristina 
longiseta, for his Macription 4 is Piss brief to be of specific value. 
As, however, the characters given by D’Udekem, in his Nouvelle 
Classification des Annélides ee ea Abranches, priser del’ Acad. 
tinct fous oe European form of the same genus. The fourth, 
nchytreus a monic I have not been able to ee 
with any species described in works at my command, and hav 
therefore named io the three anterior pairs of ventral sonibe 
after which the dorsal combs begin. This character appears to 
distinguish it from Z. socialis, if I ma PE from. th 
from which a narrow so hagus continues to a ‘Tittle back of the 
sixth ventral combs. ap re a gradual enlargement of the ali- 
mentary canal occurs, ending abruptly just back of the eighth, 
in a narrow twisted tube; and this last gradually enlarges, at the 
ninth ventral combs, into a moderate sized alimentary canal, in 
3 D’Udekem remarks: “Je n’ai pas adopté le rns a admis par Lamarek 
et Ebrenberg, parce que cette espéce ne différe des s Nais = par l’allonge- 
sli trés grand de la lévre mip Soar Ce charactére prey compagné d’aucune 
modification importante dans la form des autres organ je ne puis le considérer 
com trance’ ur servir a a Bg n genre nouveau.” ere is whit a 
marked difference in the form and position ‘of the aoa iform anterior enlarge 
the alimentary caaal, which even the statements and figures of Miiller oak Graithe 
isen indicate, between the : aids with a long upper lip or proboscis and those 
with a short one, and the manner of fission differs in these two groups as will be 
8 genus Stylaria is sag aa a good one. Ehrenberg’s , division 
of this genus however, upon of eyes is sent for I have 
seen Nais rivulosa lose them without any i appare , gassiz 
stated tha “i as a part of the normal de velopment i in mie eon 
