HYDllOZOA. 
463 
(c. ff. 8), tlio spermaries are also unnsnally numerous, and partly placed be- 
tween or below the ovaries, on the footj ovigerous spocitnons without 
testes also occur. Tlicre is no reason to regard the generative organs as 
buds or sexual individuals of a peculiar generation. Most of the cells of the 
sperniary develop into spermatozoa ; but of the ovarian cells only one deve- 
lops into an ovum; the others probably serve for its nourishment; and, 
though possessing the general character of an egg (germinal vesicle, &c.), 
it assumes a remarkable pseudo-amoeboid shape : when mature it is regularly 
ovoid, quits its abode, but remains attached to the exterior surface, is fecun- 
dated, and goes through the “ furrowing ” process, which results in the forma- 
tion of an exterior cell-layer and an interior cell-mass. The cell-layer is 
transformed into a chitinous egg-shell, separated by an interior cuticular 
membrane from the cell-mass, which dissolves into a homogeneous plasmo- 
dium. In the course of time a body-cavity is formed in the interior of this 
mass of protoplasm ; its external layer is rather suddenly transformed into an 
ectodermal layer of cells ; the shell is by-and-by dissolved or ruptured. The 
cntodermal layer only makes its appearance after the formation of the 
mouth, some time before the embryo leaves the inner membrane and starts 
into life, provided with 4-7 tentacles, and with complete differentiation of 
all its tissues. The animal has the faculty, when in want of food, of reab- 
sorbing its own buds. Jager’s diasporogenesis ” is a mistake, arising from a 
confusion between the liberated cells of the dissolving polype-body and para- 
sitical true Amoeba}. 
Hincks (7) observed fissiparous ^^frustules” in Cmwpanularia neglectaj 
and corrects the description of the nematophora ” (or sarcothecfe) of the 
Vlnmnlariidco. The “sarcostyle” is generally composed of two parts — an 
inr<U'ior, whicb alone can elongate itself iiito ‘‘pseudopodia,” and a superior, 
wliicli alone is provided with thread-cells. The function of tluiso organs is 
probably more nutritive than defensive. 
Distribution, Local Lists, ^c. 
ScHULTzic enumerates the following species as occurring in the Baltic, at 
Mecklenburg: — Hydra fusca and viridis (fresh water), Coryne squamata, 
Camyamdaria gmicidata, Sertularia ahietina, Cordyloyhora lacustris, Aurelia 
aurita, and Cyanea capillata. Arch. Ver. Mecklenb. xxiii. pp. 205 & 200. 
VKRiMLn gives a list of 7 species from the coast of North Carolina: Am. 
,T. Sc. (3) iii. p. 737. 
White AVES records a few Ily droids from the deep-sea dredgings in the 
Gulf of St. Lawrence : Ann. N. IT. (4) x. p. 345. 
Greeff briefly characterizes the hydrozoan fauna of the Canaries (“ Ma- 
deira,” &c. p. 32) ; and Metzger, Die wirbell. Thiere &c. (suqjrd, p. 421), 
p. 15, adds 4 species to the list of the species of Eastern Friesland. 12 Me- 
dusae, 8 Ilydroids, 1 Beroid (Pleurohrachia rhododactyla, Ag.), and Actinia 
equina are noticed from the Black Sea by Ulianin {sujyrh, p. 422). 
Eleutheroblastea. 
Observations on the habits and economy of Hydra vulgaris (‘ Science 
Gos.sip,’ June 1872), by Fullagar, are recorded in Q. J. Micr. Sc. xii. p. 315. 
2 H 2 
