ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
193 
Metamorphosis of Sponge-Larva.^ — Dr. G. C. J. Vosraaor has a 
short account of the metamorphosis of a species of sponge, which pro- 
bably belongs to the genus Myxilla. The free larva has an inner mass 
of cells of various kinds, covered all over by cylindrical epithelium. 
The latter soon exhibits two very distinct portions, one-seventh to one- 
eighth of the circumference having non-ciliated cells, which are more or 
less cubical in form, while the ciliated cells are very slender. There is 
no indication whatever as to what germinal layer the cells belong. In 
the central mass are a number of silicoblasts. After one or two days the 
freely-swimming larva becomes fixed. The point of fixation is at first 
in the region of the cubical cells, and the gland-cells of that region are 
active. The base of attachment gradually becomes larger ; the flagella 
disappear and gland-cells become developed. The larval epithelium 
does not disappear, but is simj)ly modified ceil by cell. The gland-cells 
which, in the larva, helped to fix the animal, secrete, in the adult, the 
slimy substance which covers the whole surface and is characteristic of 
Myxilla and some other sponges. The subdermal cavities begin as 
fissures, which gradually become wider. A little later, other canals and 
the flagellated chambers appear in the same way. 
Protozoa. 
The Genus Conchophthirus.| — Dr. A. Schuherg describes Concho- 
plitliirus anodontse Stein, and C. steenstrupii Stein, which he maintains 
to be the only known species of the above genus. The peristome of 
Heterotricha and Hypotricha had its origin in a non-ciliated groove 
extending from the anterior end to the mouth, and bordered laterally by 
undulatory membranes or the adoral zone. The absence of the ad oral 
zone, and the author’s interpretation of the secondary “ pre-oral groove ” 
(not a “peristome” sens, strict.) in ConchojditJiirus, lead him to remove 
the genus from the family Plagiotomina, and indeed from the group 
Heterotricha, to a position within Biitschli’s family Isotrichina. Schuberg 
is inclined to regard the “ pre-oral groove ” of Conchophthirus as homo- 
logous with the so-called “ gullet ” of Isotricha. 
Notes on Heliozoa.^ — M. E. Penard has found Wiesbaden a 
locality very rich both in species and individuals of Heliozoa. The 
skeletal mucilaginous zone of Acanthocystids is perfectly active, and 
behaves physiologically like the vacuolated ectosarc of Actinophrys, and 
the author is inclined to regard it as the true ectosarc. The skeleton 
may be well studied in the large Acanthocystis turfacea Carter; it is 
composed of three forms of skeletal elements — some of them are thick, 
very short, tangential scales which are so arranged as to give the appear- 
ance of a continuous membrane ; others are large radial spicules, which 
are nearly as long as the diameter of the animal itself, and yet others 
are smaller radial spicules, which are exceedingly fine and are inter- 
calated among the larger spicules. From his study of the constitution 
of these bodies the author concludes that the spicules of Acanthocystis 
are clothed with a mucilaginous varnish, within which they are formed ; 
* Tijclschr. Nederl. Dierk. Ver., ii, (1889) pp. 287-9. 
t Arbeit. Zool.-Zoot. Inst. Wurzburg (Semper), ix. (1889) pp. G.VSS (1 pi.). 
j Arch. Sci. Fhys. et Nat., xxii. (1889) pp. 52.3-39. 
1890. ‘ O 
