PORIFERA. 81 1 



foreign inclosures ; inhabitants of the sea, of brackish or fresh water ; extend from 

 the Carboniferous to the present epoch, with two sub-orders : (i) Halichondrina : 

 skeleton for the most part spicular ; spongin often almost if not quite absent ; Hali- 

 chondridae, e. g. Reniera, Halichondria ; Spongillidae, spicules smooth or spinose, 

 no spongin, asexual gemmae, cosmopolitan and freshwater, e. g. Spongilla, Meyenia, 

 &c., see pp. 249-53 ; Desmacidonidae ; Ectyonidae, spiculose .and hispid spongin 

 fibres ; (ii) Ceratina,Keratosa,= Ceratospongiae : skeleton of spongin fibres, proper 

 spicules never present (but see note 2, p. 798); foreign inclosures, e.g. sand, spicules, 

 &c., often taken up, and present both in mesoglaea and spongin fibres ; canal-system 

 belonging to type (3) or (4) ; Spongelidae, Spongelia, Velinea, Psammoclema, Psam- 

 mopemma ; Spongidae, e. g. Euspongia, Hippospongia, &c. ; Aplysinidae ; Danvin- 

 ellidae, Aplysilla, Dendrilla, Darwinella. 

 See p. 253 *. 



I. Calcarea, Polejaeff, 'Report on the Calcarea,' Challenger Reports, viii. 1883; 

 von Lendenfeld, Proc. Lin. Soc. New South Wales, ix. 1885, pp. 896, 1083; 

 cf. Id. Z. A. viii. 1885; Haeckel, Die Kalkschwamme, 3 vols. Berlin, 1872. 



Ascetta=Leucosolenia, MetschnikofT, Z. W. Z. xxxii. 1879, p. 358; Homoderma, 

 von Lendenfeld, op. cit. p. 903 ; Sycandra (=Sycori) raphanus, Schulze, Z. W. Z. 

 xxv. Suppl. 1875 ; Leucandra (Leuconid] aspera, Vosmaer, Tijdschrift Nederl. 

 Dierk, Vereen, v. 1881 ; cf. Id. Mitth. Zool. Stat. Naples, v. 1884, p. 483. 



Histology and nervous system, von Lendenfeld, op. cit. p. 977 ; Z. A. viii. 1885, 

 p. 47, p. 448, and A. N. H. (5), xvii. p. 376; Synocils, Id. Z. A. x. 1887. 



Sperm formation in Sycandra (Sycon) raphanus, PoldjaefT, SB. Akad. Wien, 

 Ixxxvi. Abth. i. 1883 ; Id. op. cit. supra, p. 33. 



Development of Ascetta and later stages of Sycandra, Metschnikoff, op. cit. p. 362 ; 

 of Sycandra raphanus, Schulze, op. cit. and Z. W. Z. xxvii. 1876 ; xxxi. 1878 ; cf. 

 Keller, Z. W. Z. xxx. 1878, p. 585. Amphigastrula in various Calcarea, Pole'jaefT, 

 op. cit. p. 32. 



Gemmation of Leucosolenia botryoides, Vasseur, A. Z. Expt. viii. 1879-80. 



II. Non-Calcarea, 



Hyalospongiae. Structure, classification, Schulze, Abhandl. Akad. Wiss. Berlin, 

 1887 (i) ; Euplectella, Id. Trans. Royal Soc. Edinburgh, xxix. 1880; Max 

 Schultze, Die Hyalonemen, Bonn, 1860; Hexactinellidae, Marshall, Z. W. Z. xxv. 

 Suppl. 1875; xxvii. 1876. 



Spiculispongiae. Stelletta, Geodia, Isops, Pachymatisma, Tetilla crantum=. 

 Craniella, Thenea, Sollas, ' Sponge fauna of Norway,' A. N. H. (5), v. 1880 ; ix. 1^82; 

 Tetilla, Tethya, Selenka, Z. W. Z. xxxiii. 1880; Tetilla japonica, Lampe, A. N. 52, 

 (i), 1886 ; Tethya lyncurium, Deszo, A. M. A. xvi. 1879 ; xvii. 1880 ; ^Plakinidae*, 

 Schulze, Z. W. Z. xxxiv. 1880; * Corticium, Id. op. cit. xxxv. 1881 ; Chondrosidae, 

 Schulze, Z. W. Z. xxxix. 1877, von Lendenfeld, Proc. Lin. Soc. New South Wales, 

 x. 1886, p. 10 ; * Halisarcidae (=Oscarella lobularis, Halisarca Dujardini}, Schulze, 

 Z. W. Z. xxviii. 1877 ; Bajalus, von Lendenfeld, op. cit. x. p. 5; cf. Id. on affinities 

 of Myxospongiae, Z. A. viii. 1885 ; *Clione, Nassonow, Z. W. Z. xxxix. 1885. 



1 A paper by von Lendenfeld on the classification and systematic position of Sponges is just 

 published in the P. Z. S. for 1886 ; cf. Z. A. ix. p. 335, and Spengel's Zool. Jahrbiicher, ii. (2), 1887. 



2 A single star before a name indicates that the larval form is described partially or completely, 

 a double star that further stages of development have been investigated. 



