BY R. VON LEXDENFELD, PH.D. 1149 



of the ciliated tubes. Numerous young ova, particularly in the 

 particularly in the Mesoderm of the peduncle. Two oscular 

 frills of Acerates. 



Figs. 16-21. — Homoderma Sycaiidra. R. v. L. The Metamorphosis from 

 the simple sackshaped Ascon to the adult, but smal vSycon. 



Figs. 22-23. — Homoderma Sycandra. R. v. L. Acerate spicules of the tufts 

 on the ciliated tubes. 



Figs. 24-26. — Homoderma Sycandra. R. v. L. Quadriradiate spicules of the 

 Parenchyma. 



Figs. 27-29. — Homoderma Sycandra. R. v. L. Triradiate spicules of the 

 Parenchyma. 



Figs. 30-31. — Homoderma Sycandra. R. v. L. Quadriradiate spicules of 

 the gastral wall. 



Fig. 32. — Homoderma Sycandra. R. v. L. Transverse section through the 

 middle of Sponge individual. Combined picture. 



Fig. 33. — Homoderma Sycandra. R. v. L. Transverse section through half 

 the upper part of the Sponge Osmic Acid. Picrocarmin, F. Oc. II. 

 This section shows the distribution of the different spicules. In 

 the Mesoderm there is a large oval Ovum. The spicules are 

 covered by sheaths, particularly those which protrude into the 

 Gastral cavity show these sheaths very clearly. Protruding 

 triradiates of the regular kind of fig. 27, are exposed in the 

 section. These are rare hidden by the tufts of acerates, which 

 are parallel to one another, and immersed only a very short 

 distance. 



Fig. 34. — Leucopsis pedunculata. R. v L. Longitudinal section. Osmic 

 Acid, the dots represent the flagellate cells covering the inner 

 surface of the Ascon tubes which have become in this specie 

 isolated ciliated chambers, with one large exhalent pore to each. 

 The shape of these chambers is irregular. 



Figs. 35, 36. — Sycandra Ramsayi. R. v. L. Seen en face (35) and en 

 profile (36.) Photographed from a spirit specimen. 



Fig. 37-— Sycandra Ramsayi. R. v. L. Transverse section combined 

 picture. C. Oc. I. The inter or inhalent canals are particularly 

 wide, and both these and the ciliated tubes remarkable for their 

 regularity and straightness. The tufts of spicules are disposed 

 tangentally on the summits of the ciliated tubes. 



