Today deals with two versions of the same manuscript, entitled “Der Naturen Bloeme” by Jacob van Maerlant . There are several molluscs in these documents, but we focus here on two of them, Limax and Testudo.
The first version originated in Flanders c. 1350 . On folio 109v one of the column miniatures illustrates Testudo. This ‘humanised’ snail has two pointed ears, an eye, nostril, and a mouth with dents; it looks very grim and could also be seen as a malacomorph hybrid showing a dog-head (or even a bat). The shell is dextral, with three whorls showing axial marks. This may be considered an iconographic paraphrase of older illustrations, e.g. items #38, #29.
On folio 133r Limax is shown. It is a stylised illustration of a slug, with an eye and mouth; one long pinnacle on the head may be representing the tentacles, although this seems odd to me. As far as I know this is the oldest representation of a slug, however, with some doubt. The accompanying text reads: “Limaxs es ene maniere van slecken / Dien wi sien haer seluen recken / Ende traghelike hene gaen / Experimentator doet verstaan / Datsoe tewintre es verloren / Te lentine so comt soe voren / Ende segghen dat dat bloet van hare / Die porrekine so vaste sluut / Datter gheen haer mee gaet vut / Ende daer puusten wassen in wonden / Men wriifse ontwee tien stonden / Dat soese ghenesen doet / Van dezen wormen weset vroet / Dese ne leghet in ghene scelle / Maer soe cruupt in haers selues velle.” The message of this Medieval Dutch text is that the slug’s slime may be healthy.
The second version of the manuscript originated more than a century later, either in Flanders or in Utrecht . In this version, the order of the animals is different. Limax is treated on folio 090v, showing a coarser animal. The pinnacle is pointing forward, and no mouth is shown.
For Testudo there are two miniatures, each with their own description. Folio 070r shows a figure similar to folio 109v of the first edition. However, the shell seems drifting on gulfs, thus suggesting a marine species. This is being cooroborated if we read the text: “Testudo dats slecke in latiin / Die in India so groot siin / Als plinius ende ander tellen / Dat liede wonen in haren scellen / Ende si van heilande theilande varen / Indie rode see daer mede te waren”. 
In we Folio 093r undoubtedly illustrates a land snail, with two tentacles, an eye-spot and a mouth. The reddish, dextral shell has more than three whorls, and shows marks suggesting rather close ribs; the aperture is relatively narrow. The text reads: “Testudo es die name der slecken / Die haer can in haer huus decken / Ende schiint oft ware marberiin / Ende dat verhart dat sonneschiin / Van haren lime ende makent hart / Som siin si root som bont som swart / Ist datmen werpet vp hare sout / So verderuet met ghewout / So datter of bliiuet harde cleene / Sonder een luttel bloets allene / Ende dats goed te medicinen / Aldus doetse dat soud dwinen.” From the 5th line it can be deduced that an epiphragm (dried slime closing the aperture) was made, and thus it is a land snail.
It may therefore be concluded that Testudo can refer to two different types of snails, and the first land snail in a Dutch manuscript only appeared in the second half of the 15th century.
 I am grateful to Nes van Hulzen, who suggested Der Naturen Bloeme as medieval Dutch literature with snail illustrations, thus laying one of the corner stones for this blog.
 KBH, Ms. KA 16, 164 ff. http://manuscripts.kb.nl/show/manuscript/KA+16. Dated c. 1350.
 KBH, Ms. 76 E 4, 152 ff. http://manuscripts.kb.nl/show/manuscript/76+E+4. Dated c. 1450–1500.
 Referring to occurrence in the Red Sea. From a transcription of Ms. KA 16 by Ed van der Vlist, curator medieval manuscripts KBH, whose kind cooperation is here gratefully acknowledged.