HYDEOZOA. 
Ccel 9 
numerouB short permanent tentacles, and the attachment of the young 
animal by a kind of sucker, placed at the ab-oral extremity of the body, 
are the most characteristic peculiarities of the organization of this stage. 
Among the more remarkable facts of the organization of Myriothela , 
resulting from Allman’s exceedingly careful and minute investigation, 
are the internal ^;^7/^-like prolongations from the endoderm, in the gastric 
cavities of the hydranth, blastostyles, and gonophores (not in the 
“claspers”); the cells of these villi and of the endodermal layer of the ten- 
tacles contain dark corpuscles. The ectoderm and endoderm are separated 
as usual by a “ hyaline lamella,” composed of a structureless internal and 
a fibrillated (muscular ?) external layer, to which are affixed the extremi- 
ties of the ramified clavate cells, forming another intermediate (nervous?) 
layer between the endoderm and the true ectodermal cells, with their 
interspersed cordate and fusiform thread-cells. In the knobs of the 
tentacula, this claviform layer is modified into a thick cap of rod- like 
(sensitive ?) tissue, from the surface of which a stratum of pedunculated 
capsules, containing peculiarly modified “ thread-cells,” is continued into 
the ectodermal covering. The modifications introduced into the corre- 
sponding tissues in the extremities of the claspers, the sucker, and the 
transitory arms of the Actinula, corroborate the conclusion that the 
bacillar tissue is of a sensitive nature, and that the ordinary thread-cells 
themselves are not without some connection with sensitive functions. 
From Grobben’s investigation ot Podocoryne (10), the following notes 
may be gathered : the spines are regarded as a peculiar kind of zooids, 
“ skeleton polypites the proliferous zooids are sometimes without ten- 
tacula ; the part played by the marginal “ spiral zooids ” (without mouth 
or tentacula, but with a head of large nematocysts) is probably that of 
defence ; they are apparently only found in male colonies. There is no 
external coenosarcal investment of the chitinous spines and stolons ; the 
muscular fibrils forming a layer on the outside of the basement-lamella are 
direct continuations of the ectodermal (“ neuro muscular ”) cells. The 
development of the sexual products in the Medusa begins at a time when 
it is still included in its cuticular capsule, and before the union of the 
radial canals into the circular vessel has taken place. The abnormal con- 
ditions of the nutritive and proliferous zooids caused by parasitic Pycno- 
gonida are described, also abnormal bifurcate spiral zooids, twin-Medusae, 
&c. 
According to Panceri (18), the seat of the luminosity in Campanularia 
is in the cells of the ectoderm, not only of the polypites, but also of the 
peduncles and stolons. 
Hydeocoeallia. 
The investigations of Moseley (15), made during the expedition of 
the “ Challenger,” have proved beyond doubt that Millepora really 
belongs to the Hydrozoa, as previously asserted by L. Agassiz, and have 
confirmed, though in a rather unexpected manner, the suspicion that the 
Stylasteridce {Stylaster, Cryptohelia, Errina, Folypora, g. n., Acanthopora, 
g. n., Lepidopora, Distichopora, Pliohothrus) are likewise Hydrozoa. As 
only preliminary reports are at hand, this abstract must be restricted to a 
