A. General Works. 3 



gosilicina 2 spec. (1 nov.) ; Clavulina 6 spec.; Halichondrina 27 spec.; Ceratina 

 1 spec. Anatomical details and figures are given for Halisarca rubra n. sp.; 

 Chalina montagui (Johnst.) Bwk. ; Axinella mammillata n. sp. ; Sciriola compacta 

 Han. [This genus closely resembles Stryphnus , but the author keeps up both 

 genera.] Further Cliona celata Grant; Stelletta collingsii (Bwk.) Soil., and Leu- 

 caltis impressa n. sp. 



Topsent f 1 ) enumerates now 88 species of sponges from Luc, the list being 

 augmented this year by 9 species. Descriptions are given of: Tethyspira (n.) 

 spitiosa (Bwk.) = Tethea spinosa Bwk. ; Suberites tenuicula (Bwk.) = Hymedesmia 

 tenuicula Bwk. 



Topsent ( 3 ) gives a preliminary account of the sponges collected by the expe- 

 ditions of the Prince of Monaco. 163 species are found, 54 of which are new. 

 A large number (118) came from the Azores. The following new genera are 

 mentioned: Rhabderemia (1 sp.), Joyeuxia (1 sp.) , Yvesia (8 sp.) , Pytheas 

 (1 sp.), Spanioplon (1 sp.). 



On the sponge-fauna of Fernando Noronha see Ridley, on fossil sponges, Meu- 

 nier, Perot, and PoiSta. 



Chatin studied the nucleus of sponge-cells. He thinks these cells exceedingly 

 suitable for nuclear studies. The shape varies considerably: elliptical, or in the 

 shape of a comma, a crescent or a horse-shoe. It may be long, flat or moniliform, 

 seldom branched. A membrane is often clearly visible. The nuclein is often 

 seen in ribbons. These are properties , which strongly recall the nuclei of Pro- 

 tozoa, and the author considers this resemblance to be of moment. 



Delage believes that in the larvae of Esperella the flagellated cells do not lie 

 externally, but send out their flagella through spaces left between globular ectoderm 

 cells. The flagellated cells are thus considered as entoderm. The flagellated 

 chambers originate each from one mother-cell, the nucleus of which divides up into 

 the nuclei of the collar-cells. The canals are formed by fissures of the central 

 mass. The original flagellated cells of the larva, which have lost their flagella, 

 are arranged round the fissures and finally line the canals. Beneath the external 

 surface originate the subdermal cavities; their roof is formed by ectodermic 

 cells, their floor by the primitively flagellated, endodermic cells. The flagel- 

 lated chambers are considered to be of mesodermic origin. The author is of 

 opinion , that his researches have made disparaitre la difference radicale et in- 

 compre'hensible entre les Eponges calcaires et les siliceuses cr. 



Korschelt & Heider give the following general review of what is known about 

 the development of sponges. Several new observations and figures are added. 

 In sponges there is a sexual and an asexual reproduction. As to the former, we 

 may say that in every sponge : 1 The sexual products originate from the so- 

 called mesoderm. 2 The ova do not possess any membrane (chorion) ; they lie in 

 a capsule, which is lined by endothelium. Here the polar bodies are eliminated 

 (according to Magdeburg's observations , not yet published) . 3 In the capsule 

 the ova undergo a total segmentation and are transformed into round or elliptical 

 larvae with cilia (planula). 4 In this state the larva becomes free. 5 After 

 swimming about for a short time, it attaches itself to some foreign object and now 

 rapidly changes into the young sponge. - - The authors distinguish three types of 

 development: 1 By the amphiblastula- stage (Syc. raphanus and many other 

 P. calcaria) . 2 By the coeloblastula- or archiblastula-stage (Oscarella lobularis 

 and probably also the Plakinidae) . Here the larva consists of a single layer of 

 flagellated cells, enclosing a fluid mass. 3 By the parenchymula-stage. The 

 larva consists of a single layer of flagellated cells, enclosing embryonic cells of 

 connective tissue. Sometimes the peripheral cells are all alike (Leucosolenia], 



