Fewkes.] 302 {October 1, 
The peculiar cells which I have mentioned are not germinative 
vesicles as their number and variations plainly indicate, but more 
especially as seen in the absence of the germinal dot. I am inclined 
to think these so-called sexual organs are unisexual, and that we have 
in these animals a case unlike Gegenbaur’s R. Hysenhardtii. 
Mr. Alex. Agassiz mentions and figures in his account of Nanomia 
a most wonderful and unique form of development of the young 
Nanomia from a bud, as well as from the egg; he considers an egg de- 
velopment also to be present, but apparently did not find the very 
early stage of the egg.1 Such a method of development by a bud has 
only been observed in this single case, and by him alone. Rhizo- 
physa may have a similar form of development in these botryoidal 
structures. Certainly there is very little resemblance between the 
oldest observed stage, which I have figured, and the egg or male 
organ as found among the Siphonophorae. 
Note. The following is not a complete list of the literature of the Siphono- 
phorae but of works mentioned in this paper. 
A. AGASSIZ. Proc. Bost. Soc. Nat. Hist. 1863. 
North American Acalephae. 1865. 
Letter to Mr. C. P. Patterson, Bull. Mus. Comp. Zool., No. 14. 1879. 
BRANDT. Prodromus descrip. anim. ab H. Mertensio obsery. Petrop. 1835. 
CLaAus. Neue Beobachtungen, etc. Zeitschr. f. wiss. Zool., Bd. XII. 1863. 
Ueber Halistemma Tergestinum. Wien, 1878. 
DELLE CHIAJE. Descriz. et notom. degli anim. invert. della Sicilia. Tom. y. 
EscHSCHOLTZ. System der Acalephen. 
EYSENHARDT. Nov. act. Leop. Carol. Tom. X. 1821. 
FoRSKAL. Descript. animal. etc., quae in itinere orient. collegit. Harniae, 1775. 
GEGENBAUR. Beitraige zur nihern Kenntniss der Schwimmpolypen. Leip- 
zig, 1854. 
Neue Beitrage zur nihern Kenntniss, etc. 1860. 
HAECKEL. Zur Entwickelungsgeschichte der Siphonophoren. Utrecht, 1869. 
HUXLEY. Oceanic Hydrozoa. Ray Soc., 1859. 
KEFERSTEIN UND EHLERS. Zoologische Beitrage. Leipzig, 1861. 
K6LLIKER. Die Schwimmpolypen oder Siphonophoren yon Messina. Leip- 
zig, 1853. 
KOWALEWSKY. Gottinger Nachrichten. 1868. 
Lesson. Acalephes. 
1 According to Metschnikoff, Nanomia cara is simply a member of the old genus 
Stephanomia. He does not seem to give importance enough to this peculiar 
budding development. Its existence in one and not in the other, would be sufii- 
cient cause for a generic difference, yet it remains to be seen whether such a 
method of reproduction does occur in Stephanomia; further study of the history 
of the young of Nanomia is also needed 
