258 Porifera. 
Die Original-Diagnose lautet: „A cylindrical or ovate sponge, with thick walls surroun- 
ding the main excurrent canal, which, as a cylindrical tube, extend axially almost to the 
base of the sponge, and opens unconstrietedly at the summit in a circular oscule. The Sponge- 
walls are traversed by two'sets of smaller canals, one incurrent, which, commeneing in small 
round ostia evenly dispersed on the external surface, continue inwards obliquely downwards 
towards the axis; the other excurrent, which, crossing the incurrent canals, run more or less 
parallel to the curved upper margin of the sponge and finally open into the main excurrent 
canal. Skeleton Euretid, i. e. a simple Dictyonine network with imperforate nodes; dermal 
skeleton not preserved.“ 
f. Genus XIV. Mastodietyum Sollas 1883. 
Blattartig, verästelt. Auf der Oberfläche zahlreiche papillenartige 
Auswüchse. Keine Deekschicht. Oolith. 
Beisp. M. Whidborni Soll. Abbild. bei Sollas T. XX, Fig. 7—9. 
Wicht. Liter. Sollas in Quart. Journ. Geol. Soc. 1883, p. 544 ff. 
Die Original-Diagnose lautet: „A branching, leaf-like expansion, bearing on the upper 
surface numerous mamillary processus, or teat-like individuals, resembling diminutive Emplocae. 
Each is perforated axially by a cylindrical canal, extending nearly to the base, and opening 
above in an apical oscule with a sharply defined circular margin. Incurrent ostia are dis- 
persed at about equal distances over the interior, and the incurrent and smaller excurrent 
canals run through the walls at right angles to the surface, alternating with each other. 
Skeleton Euretid; dermal skeleton absent.“ 
Es giebt nun noch einige (fossile) Gattungen, welche nach Zittel wahr- 
scheinlich hierher gehören, nämlich: 
f. Amphispongia Salter (Mem. geol. Surv. Explan. Edinb. Sheet, etc. 
Pl. 2, Fig. 3). 
f. Calathium Billings (26, Vol. I, p. 208-211, 335-358). Silur. 
f. Trachyum Billings (ibid. p. 211). Silur. 
f. ‚ Archaeocyathus Billings (ibid. p. 3—5, 354). Silur. 
f.  Steganodietyum M’Coy (Palaeoz. Fossils of the Cambridge Museum, 
T. 2, A, Fig. 1—4), Devon. 
n rchaeocyathellus Ford. 
f 
f. Protocyathus Ford. 
f. Brachiospongia Marsh (Amer. Journ. Se. Arts (21, XLIX, 1867, p. 88). 
f 
ıY 
Rhabdaria Billings. 
Acanthospongia M’Coy (Griff. Syn. 1846) p. p. 
f. Familia II. Coseinoporidae. 
Schwammkörper becherförmig, sternförmig oder ästig, öfters 
zusammengedrückt. Radialcanäle sehr zahlreich, einfach, gerade, 
blind. Ostien klein, Skelet feinmaschig, dicht, steinartig, durch 
die zahlreichen Radialcanäle an einer regelmässigen Bildung von 
cubischen Maschen gehindert. Kreuzungsknoten der Sechsstrahler 
En 

