6 MUSEUM, BROOKLYN INSTITUTE OF ARTS AND SCIENCES. 
the more primitive and universal co-operation of both ectoderm and ento- 
derm. 
'New Species. Two new species were established, Lymnorea Alexandri, 
named in honor of the author's constant friend, Alexander Agassiz. It is the 
most abundant medusa of the Bahama Banks throughout the summer. 
The other new form has been named Parvanemus degeneratus, and is the 
most degenerate free-swimming hydromedusa yet described. It lacks tenta- 
cles, sense organs, and peripheral vascular system. It swims, however, with 
great activity, but is short-lived. In this form nature appears to have per- 
formed Loeb's experiment, in which, as is well known, he cut away the rim of 
the bell, depriving the medusa of tentacles and sense organs. Yet the bell 
still contracted rhythmically when placed in a solution having the same os- 
motic pressure as sea water, but liaving no cah-ium or potassium ions, 
Murbach, 1903 ; Amer. Journ. Physiology, X, p. 201, has shown, however, 
that in Gonionemus the marginal otocysts have nothing to do with the main- 
tenance of equilibrium, but that it is probable "that muscular sensation 
(largely in the velum) is the seat of static function in Gonionemus and in 
hydromedusse." It is interesting to observe that the velum of Parvanemus is 
exceptionally large and provided with powerful muscles. Such "muscular 
sensation" is not always found in the velum, however, for in Rhacostoma dis- 
par the bell opening is much reduced and the medusa is propelled by the 
movements of its widely open mouth. Bull. Mus. Comp. Zool. at Harvard 
Coll., Vol. XXXVII, p. 61, 1900. 
DESCRIPTION OF SPECIES. 
For the sake of completeness we present a brief description of all species 
of Hydromedusse known from the Bahamas. 
The classification is essentially that of Haeckel. 
HYDROMEDUSiE. 
Parvanemus degeneratus, gen. et. sp. nov. 
Fig. 22, Plate III. 
Generic Characters: Parvanemus: Codoiiida' without tentacles, radial 
canals, or circular vessel. 
