. MILIOLIDA. - 19 
General characters——Numerous short, subcylindrical chambers, forming a long linear 
shell, of variable dimensions, truncate at one end, and perforated with either a single 
(often dendritic) aperture, or with several pores; and at the other (first-formed) end 
curled into a little crook or knob: this, when small, is often broken off, leaving a tapering, 
awl-shaped, striated shell, delicate in shape and white in colour. 
Sp. cylindracea is common in the Mediterranean, Red, and Indian Seas. We have it 
small and very rare from the Crag of Sudbourne (specimen lost). 
much confusion in the nomenclature; and it will be useful here to point out some of the best-marked 
forms of Peneroplis and its varieties, in chronological order :— 
1775. Nautitus pertusus, Forskal (type: comprising broad and narrow varieties). Peneroplis 
pertusus, Forsk. 
1781. — rectus, Spengler (including a variety of Articulina). 
1785. — umMBILIcaTus, Linné (flat, curled like a crozier-head). Peneroplis umbilicatus, 
Linn. 
1785. — SEMILITUUS, Linné (flat, with crozier-head and short stem). Peneroplis 
semilituus, Linn. 
1788. — Lituus, Gmelin (long, slender, cylindric, with one end curled). P. (Spirolina) 
lituus, Gm. 
1791. — (Lituvs) arretinus, Batsch (narrow, flat, curled at end). P. arietinus, Batsch. 
1791. — —  acicutarts, Id.  P. (Spirolina) lituus, Gm. 
1803. ~ PLANATUS, Fichtel and Moll. (broad forms). P. planatus, F. and M. 
1804. Sprrotina (Sprro.inites) DEPRESSA, Lamarck (two subvarietal forms; one nearly lenti- 
cular, Dendritina ?). P. pertusus, Forsk. 
1804. _ a CYLINDRACEA, Jd. (long, sub-cylindrical, with one end curled). 
P. (Spirolina) eylindracea, Lam. 
1808. PENEROPLIS LANATUS, Montfort. P. planatus, F. and M. 
1816. CRIsTELLARIA PLANATA, Cr. pDILATATA, Lamarck; and 1822, Cr. sauamuLa, Lam. 
P. planatus, F. and M. 
1826. Denpritina arBuscuta, D’Ord. (lenticular). P. (Dendritina) arbuscula, D’Orb. 
1839. Coscrnosprra (Sprrotina) Hempricurt, Lhrenberg (stout, cylindric, with boldly curved 
end). LP. (Spirolina) cylindracea, Lam. 
Although Forskal did not figure P. pertusus, yet there can be no mistake in regarding the following 
escription as especially belonging to it (‘ Descript. Anim. Itin. Orient.,’ 1775, p. 125): “ Having com- 
ressed whorls, transversely suleated, and marked with slight longitudinal striz ; at the aperture per-+ 
forated with pores. Colour snow-white. ... . Whorls straight at the base [top], often dilated, some- 
times linear ; at the apex [earliest part] convolutely spiral.’ It was from Suez, Red Sea. 
