PERONIDELLA PISTILLIFORMIS. 213 
are crowded together irregularly, so that in a section of the chert some are cut 
transversely or obliquely, whilst others show their complete forms (PI. XIII, fig. 6). 
Hitherto no definite evidence of the much smaller gemmule spicules has been 
discovered, and consequently it is not quite certain that the skeletal spicules really 
belong to Spongilla or to the allied genus Meyenia. The acerate skeleton 
spicules are about half as large again as those of the existing Spongilla 
lacustris, Linn. 
Distribution.—Chert in the Purbeck limestones at Stare Cove, near Lulworth, 
Dorsetshire (Coll. J. F. Young; Geol. Survey Museum, Jermyn Street). 
Orper.—CALCISPONGLA. 
Family.— PHARETRONES. 
Genus.—PERONIDELLA,! Zittel. 
21. PERONIDELLA PISTILLIFORMIS, Lamouroux, sp. Plate XIV, figs. 1—ld. 
1821. Sponera PIsTILLIFoRMIS, Lamex. Exposition méthod., p. 88, pl. lxxxiv, 
fig. 6. 
1840-7. Scyputa pisTrnLiFormis, Michelin. Icon. Zooph., p. 250, pl. lviii, 
figs. da, b. 
1854. — — Morris. Cat. Brit. Foss., p. 29. 
1854. Sponeata cymosa (?), Morris. Ibid., p. 30. 
1859. Potyomnta prstinLorpEs, Fromentel. Mém. Soc. Linn. de Normandie, 
vol. xi, No. 2, p. 32, pl. i, fig. 8. 
1878. PERONELLA PISTILLIFORMIS, Zittel. Studien, ili, p. 32. 
1883. _ REPENS, Sollas. Quart. Journ. Geol. Soc., vol. xxxix, p. 548, 
pl. xxi. fig. 31. 
1883. — PISTILLIFORMIS, Hinde. Cat. Foss. Sponges, p. 165, pl. xxxiii, 
figs. 1, la. 
Sponges growing in bushy stocks or colonies, usually with a thickened 
procumbent base from which stems or branches are given off, which may either 
diverge or grow more or less in contact; in this latter case they frequently 
amalgamate laterally. The stems are either simple, or with lateral buds which 
1 Since the definition of this genus was given in Part II, p. 175, it has been discovered that the 
term “ Peronella”’ was informally proposed by Dr. Gray in 1855, and adopted by A. Agassiz in 1872, 
for a genus or sub-genus of Echinoderms, and Prof. von Zittel has consequently proposed to modify 
the name for this genus of Calcisponges to “ Peronidella.” 
EE 
