1886.] POSITION AND CLASSIFICATION OF SPONGES, 581 
1. Group Liraistrpa, Zittel. 
Body stony, with a central gastral cavity or numerous vertical 
tubes. Spicules more or less clearly tetraxon, often branched. 
Besides these, sometimes monaxon spicules and flesh-spicules. The 
skeleton-spicules are interwoven so as to form a dense skeleton. 
1. Familia Ru1zoMoRINID«&, Zittel. 
Spicules irregularly branched ; form irregular fibres, or are loosely 
interwoven. Forked anchors always present. 
Arabescula, Carter; Corallistes, Schmidt ; Heterophymia, Pomel ; 
Seliscothon, Zittel ; MacAndrewia, Gray ; Azorica, Carter; Leioder- 
matium, Schmidt ; and the fossil genera :—Cnemidiastrum, Coral- 
lidium, Hyalotragos, Pyrgochonia, Discostroma, Leiodorella, Episto- 
mella, Platychonia, Bolidium, Astrobolia, and Chonella of Zittel; 
Plococonia, Pomel ; Chenendopora, Lamouroux ; Verruculina, Zittel ; 
Amphithelion, Zittel; Stychophyma, Pomel; Allomera, Pomel ; 
Pleuromera, Pomel; Perimera, Pomel; Meta, Pomel; WMarisca, 
Pomel ; Pomelia, Zittel; Jereica, Zittel ; Calocorypha, Zittel; Scy- 
talia, Zittel; Stachyspongia, Zittel; Pachinion, Zittel. © 
2. Familia ANOMOCLADINID, Zittel. 
Spicules rod-shaped with terminal tufts of branches. The approxi- 
mating ends of the spicules coalesce and form knots. In this way a 
regular triaxial network is formed. 
Vetulina, Schmidt; and the fossil genera Mastosia, Cylindrophyma, 
Melonella, and Protachilleum, Zittel, and Paleomanon and Astylo- 
spongia, Roemer. 
3. Familia TETRACLADINIDA, Zittel. 
Spicules tetractinellid with terminal branches. 
Theonella, Gray ; Rhacodiscula, Zittel ; Discodermia, Bocage ; Ka- 
liapsis, Bowerbank ; Collectella, Schmidt ; Collinella, Schmidt; and 
the fossil genera :—Aulocopium, Oswald; Phymatella, Aulaxinia, 
Callopegma, and Trachysycon, Zittel ; Siphonia, Parkinson; Halli- 
rhoa, Jerea, Lamouroux; Marginospongia, d’Orbigny ; Nelumbia, 
Pomel; Polyjerea, Fromentel; Astrocladia, Zittel ; Bolospongia, 
Hinde ; Thecosiphonia, Zittel; Calymmatina, Zittel; Turonia, Mi- 
chelin ; Kalpinella, Thamnospongia, and Pholidocladia, Hinde; Ra- 
gadinia, Zittel; Plinthosella, Zittel ; Spongodiscus, Zittel ; Phyma- 
plectia, Hinde; Rhopalospongia, Hinde. 
To this Subordo also the fossil family Megamorinidz belongs. 
11. Group CHorisTIDaA, Sollas. 
With tetraxon spicules of regular shape. 
i. Tribus Tetradina, Sollas. 
The chief spicules are tetract, with equal rays and candelabras. 
i. Subtribus Microcamera, nov. 
With small chambers. 
