\ Porifera. 



hollow and many smaller ones; pseudoscula are inhabited by symbiotic or- 

 ganisms or filled with slime ; on the lower surface are deep pits, often imperforate. 

 The exposed convex surfaces with thick rind are perforated by fine afferent pores 

 leading into a plexus of fine canals outside the sterraster layer ; this is perforated 

 at intervals by afferent canal- stems leading to chones. From each chone a 

 canal (sometimes uniting with its neighbours) leads into the pulp. From the pear- 

 shaped flagellate chambers special canals unite into wider and wider efferent 

 canals; the final stems, often straight and parallel like organ-pipes, have dome- 

 like terminations under the rind communicating directly or by fine canals with 

 the efferent chones. These are rarely shut ; from each a canal pierces the ster- 

 rastral crust and branches to the efferent pores ; pores and chones are wider than 

 in the afferent system. In G. luberosa pores are distributed as in G. conchilega. - 

 Caminus vulcani. From afferent pores in the concave fields fine canals unite in 

 vertical tubes which pierce the sterraster- crust to the chones; from each chone a 

 canal leads inward, two often uniting; they pass deep into the pulp. Chambers 

 spheroidal, broader than long, efferent canals narrow. - - Camimlla loricuta n. 

 Each little prominence bears an afferent pore from which a canal passes to a 

 chonal sphincter under the rind; from the sphincter branching canals penetrate the 

 pulp. Chambers broader than long, with special efferent canals. - The Digi- 

 tellen of 0. lobularis are projecting poison-glands. 



Lendenfeld ( 4 ) finds Schmidt's original examples of Suberites fruticosus and crambe 

 to be a new genus (Tetranthella] of Lithistida Anoplia; having spongin fibres con- 

 taining styles and tylostyles, but tetracrepid desmas on the surfaces of the fibres. - 

 Vosmaer( 3 ) found the two species identical 14 years ago and gave the name Crambe 

 fruticosa , the so-called tetracrepid desmas have unbranched axial canals , and 

 the chelae L. considers accidental probably belong to the sponge. - - According 

 to Lendenfeld ( 5 ) Vosmaer's name of C. cannot stand. - - Topsent( 7 ), quoting 

 Topsent( 4 ), agrees, and finds that T. possesses no chelae; but the desmoid spicules 

 are inconstant in occurrence and form ; they play the role of microscleres, com- 

 parable to the stars of Trikenlrion ; the flagellate chambers are eurypylous, and 

 the sponge is no Lithistid or Tetractinellid. 



Topsent( 7 ), adopting mainly Sollas's classification of Tetractinellida, ejects the 

 Epipolasidae, Samidae, Microsclerophora, and some genera, adding 

 the Desmanthidae and the Stellettid genus Sanidastrella. Among 25 French 

 species there is one Lithistid, Desmanthus n. (= Aciculites incntstans, Tops.), con- 

 stituting the Desmanthidae n. fam., Lithistida Hoplophora without micro- 

 scleres. -- Canal- system. - - Erylus stellifer. Afferent chones uniporal, oscula 

 open. - - Pachymatisma johnstonia, Example of cribriporal chones. From each 

 stomion runs a narrow canal, a group of these compose the ectochone, and unite 

 into one tube, the endochoue, to pierce the sterrastral layer and open in the system 

 of superficial cavities opposite a pore. Oscula open. There are powerful dia- 

 phragms at the debouchement of the efferent canals, so that no contraction of the 

 oscula is necessary. - - Caminus vulcani. As P. j., areas of stomions stellate; 

 Schmidt's description inexact.-- Cydonium conchilegum. Oscula and pores cribri- 

 poral. On teasing off the ectosom the endochones can be seen with the naked eye. 



- C. gigas. do. do. The osculiferous area often near the base of the sponge. - 

 Isops. Oscula and pores uniporal. /. intuta. A single stomion gives access to 

 the ectochone, which is continued without break as the endochone through the 

 sterrastral layer. Stelletta Grubei. Pores cribriporal, oscula small and scattered. 

 Penares hvlleri. Uniporal afferent chones, undifferentiated into ectochone and 

 'endochone. Chambers aphodal. Oscula solitary and rare. P. candidata do. do., 

 superficial cavities very large. - - Sanidastrella coronata. Afferent chones cribri- 



