490 
CaCLENTEKATA. 
Hydra, but being entirely destitute of tentacles. The body consists of two 
well-marked layers, outer and inner ; the outer has no pigment, but contains 
large thread-cells. The author, however, could not detect any epithelial 
layer lining the cavity of the body, nor did he find cilia in any part. No 
sexual reproduction or sexual form Avas observed ; but the polyp reproduced 
itself freely by division. To this form Greeff applies the name oi Protohydra 
leuckarti, and looks on it as one of the oldest surviving stock-forms of the 
Coelenterata, and especially of the Hy droid type. Hah. Ostend, among 
diatoms and algae. 
Metzger (JB. Ges. Hann. 1869-70) gives the following list from the East- 
Erisian coast : — 
Mesonema henleana, Koll. ; Callirhoe hasteriana, Peron ; Thaiimantias he- 
misphcerica, P^ron ; Tuhtdaria coronata, Van Beneden ; T, dumortierii, Van 
Ben. j Syncoryne pusilla, Gaert. ] Hydractinia echinata, Van Ben. j Campanu- 
laria yelatinosa, Link. ; C. genicidata, Lmli. j Clythia voliibilis, Link, j Sertu- 
laria cnpt'essina, L. j S. opcrcidata, L. ; Thoa halecina, L. j Dynamena pumila, 
L. ; Plumidaria faloata, L. ; P. pinnata, 1j. j P. cristata, Lmk. 
Dipleurosoma, g. n., Boeck (J. <?.). Bemarkable for its striking bilateral 
symmetry. D. typica, sp. n., south-Avestern coast of Norway. I), stuvitzi, 
sp. n., NeAvfoiindland. 
SlPHONOPIIORA. 
Metschnikofp contributes {1. c.) some notes on the development of 
Galeolaria aurantiaca, Halisternma ruhrum {Agalma ruhrum, Vogt), Hali- 
stemma, sp., Agalma punctatum, and Physophora hydrostatica. 
Stuart (Arch. Anat. Phys. 1870, p. 366) gives an account of the 
development of the medusa-buds in Velella spirans. He believes that 
Chrysomitra s^iVaws = medusid of Velella. 
Discopiiora. 
^ Schneider (Arch. mikr. Anat. vi. p. 363) describes the structure of tlio 
scyphistome and strobile forms of Aurelia aurita, obtained on Zostera-leaves 
from Kiel in Eeb. 1869. According to those researches tlie author holds it 
now proved that Scyphistoma does not represent the Hydroid, but the Medu- 
soid form of the Coelenterata. 
IIiNCKS points out that the observations communicated by Mr. M^Andrew 
to Dr. Gray, and published in tlio Annals of Nat. Hist, for Oct. 1869, of Sea- 
jellies {^Medusa ecquorea, Eorskfil) having been seen lying on their backs at 
the bottom of the clear waters of the lied Sea, Avith their tentacles ex- 
panded like a flower, had long ago been made by Mertens, who, as quoted 
by Agassiz, had constantly found 3Iedusa (Polyclo)iio) mertensii in the lagoons 
of Ualau, with their arms spread and turned upAvards.” Note on the habits 
of the Discopiiora, Ann. N. H. (4) v. p. 145. 
Brandt (Mem. Pet. 1870) describes with great minuteness the gastrovas- 
cular system of Rhizostoma cuvieri. lie points out a certain amount of bi- 
lateral symmetry in the body of Rhizostoma, and found also in young indi- 
viduals, from 8 to 20 centims. high, the remains of the original central 
mouth. He rejects the idea that these animals are in any sense to be con- 
sidered colonies, agreeing with Fritz Miiller that Ave may often see a 
similar, though temporary, polystomy in Hydroid Medusie, Avhen the edges 
