ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
211 
Echinoderma. 
Pseudopodia in Echinoderm Ova and Embryonic Cells.* * * § — Gwendolen 
F. Andrews observes that the ova, polar bodies, blastomeres, and even 
later embryonic cells, of starfish and sea-urchins, give off delicate ana- 
stomosing pseudopodial filaments like those of Rhizopods. It is claimed 
that these are concerned in the formation of the egg-membrane, that they 
connect the cells during cleavage and gastrulation so that the protoplasm 
is continuous, and that they may be the basis of cytotropism and of co- 
ordinating communication in embryonic cell-aggregates. The obser- 
vations are described under the title, “ Spinning powers of certain 
eggs.” 
Palaeozoic Ophiuroids.-j-— Dr. J. W. Gregory gives a synopsis of a 
classification with diagnoses of some of the genera. He recognises two 
orders : — (1) Lysophiurae (ambulacral ossicles alternate, free ; no ventral 
arm-plates) ; (2) Streptophiurae Bell (vertebral ossicles present with 
more or less Streptospondyline articulations). The first order includes 
Protasteridae and Palaeophiuridae ; the second includes Ophiurinidae, 
Lapworthuridse, Eoluidse, Onychasteridae, and Eucladiidae. 
Muscle-Fibres of Holothurians.J — Dr. N. Iwanzoff finds that if the 
internal organs of Holothuria tubulosa and Stichopus regalis be treated 
intra vitarn with methylen-blue, by injection or otherwise, certain 
muscle-elements react like nervous elements. It seems as if those 
elements which behave in this way were in a normal state of exhaustion, 
marked by the presence of a granular product of metabolism, which has 
a strong affinity for methylen-blue. Perhaps the same is true of nervous 
elements. 
Ccelentera. 
Diversity of Structure in Metridium.§ — Prof. G. H. Parker shows 
that uniformity of structure is by no means a general characteristic of 
Metridium marginatum Milne Edw. As in some other Actinians, there 
are variations in the number of siphonoglyphs and in the number and 
relations of the mesenteries. The author distinguishes monoglyphic 
and diglyphic types ; but it is uncertain whether these are varieties or 
whether the species is dimorphic. It is possible that the two forms 
may be associated with sexual and asexual reproduction. 
Porifera. 
Sponges of Amboina.|] — Dr. E. TopSent describes a collection from 
the Bay of Amboina. It included more than 80 species, of which 27 
were new species or varieties. The collection was made in the Madre- 
pore zone, and was characterised by the absence of Hexactinellida, the 
abundance of Monaxonida (especially Haploscleridas), a sparse represen- 
tation of Calcarea, a notable proportion of Tetractinellida and Mono- 
ceratina. The Carnosa were represented by three interesting forms : — 
* Journ. Morphol., 1807, pp. 367-89. See Amer. Nat., xxxi. (1897) pp. 242-5. 
t Proc. Zool. Soc., part 3, 1896 (published 1897), pp. 1028-14. 
X Arch. f. Mikr. Anat., xlix. (1897) pp. 103-13 (1 pi.). 
§ Bull. Mus. Comp. Zool. Harvard, xxx. (1897) pp. 259-73 (1 pi.). 
U Rev. Suisse Zool., iv. (1897) pp. 421-87 (4 pis.). 
