A. General Works. 3 



A. General Works. 



Epithelium, see infra p 8, 10, Bidder ( 1 , 2 ); Excretion, see ibid. - - See also 

 Pocta, Rauff ( 4 ), Topsent (), and, supra, Protozoa p 10 Dreyer. Occurrence of 

 iron in tissues, s. infra, Allg. Biologie p 14 R. Schneider. 



Vosmaer states once more that the words osculum and pore are used for 

 things which are by no means homologous. He attempts therefore to define more 

 strictly what may be called osculum etc. in various sponges, and what decidedly 

 not. The simplest Homocoela represent the most primitive canal system, the 

 ground type of which is a simple sac. Likewise can the canal system of Hex- 

 actinellida be derived from a sac type. The system of Leuconidae and Syconidae 

 can be derived from that of Asconidae. Thus can every type of known canal 

 system be derived (on theoretic grounds) from the sac type. The main (exhalant) 

 tube of Leucosolenia stipitata is equivalent to the main tube of L. (ripodifera. The 

 chief difference between the system of this sponge and of a Sycon is that in the 

 former the whole inner surface is lined by choanocytes, and that in the latter 

 only part of it is so lined. It is thus probable that the main excurrent tube in 

 L. stipitata, L. tripodifera or in a Sycon is homologous. This central excurrent 

 cavity is called cloaca, and its aperture osculum. The apertures of the diffe- 

 rent excurrent canals, lacunae or diverticula into the cloaca are named procts. 

 E.g., in Syconidae, the procts coincide with the apopyles. Comparing the 

 anatomy of different Hexactinellids, the author concludes that for the moment 

 there is not one reason which contradicts the suggestion that the concave side of 

 the cup is homologous to the cylindrical (central) tube of others, and is thus also 

 to be regarded as a cloaca, the opening as an osculum . What we see clearly in 

 Hexactinellids we can observe, however, also in other groups ; e.g., in Synops, 

 the shallow depression corresponds to a cloaca, and the exhalaut openings which 

 are there congregated are therefore procts. A complication is found in sponges 

 like Cydonium, where each exhalant chone does not open in a single proct, but 

 with several smaller openings called proctions. The author makes an analogous 

 distinction for inhalant apertures, which are named stomas and stomions. 



Rauff ( 2 ) gives a preliminary account of fossil sponges where the siliceous 

 skeleton is changed into a calcareous one. The siliceous sponge has been imbedded 

 in the mud and the parenchyme gradually replaced by a siliceous sediment, 

 which hardened to one compact mass of chalcedone. Meantime the spicules were 

 dissolved and washed away. Finally the lacunae of these, i. e. the places where 

 spicules had been, were filled with carbonate of lime (Kalkspath). 



Hinde & Holmes describe several sponge-remains obtained from beds of 

 siliceous and siliceo-calcareous material found near the town Oamaru, South Is- 

 land, New Zealand. In general appearance the specimens resemble those of the 

 English Upper White Chalk. They are of a greyish- white tint, soft, earthy, 

 friable, and readily breaking up into a fine mud. Most of the specimens are 

 entirely siliceous. The general character of the Oamaru-rock resembles the 

 Diatom and Radiolarian oozes of the Challenger. It is probable that the fossils 

 are a deep-sea deposit. As a rule the spicules retain their original structure 

 of opalized silica. Spicules are found abundantly; but not a single fragment of 

 the sponge- itself. Monactinellidae are more numerously represented than 

 any other group. They belong to genera allied to (identical with?) Reniera, 

 Chalina, Forcepia, Acarnus, Hamacantha, Esperella, Esperiopsis, Cladorhiza, Chon- 

 drocladia, Desmacidon, Myxilla, Jop/ion, Amphilcctus, Guitarra, Melonanchora, 

 Pseudohalichondria, Plocamia, Axinella, Hymeraphia, Spirastrella, Pronax, Latrun- 

 culia, Thoosa, Alectona. To these 24 genera belong 70 species. Further were 



