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EOCENE MOLLUSCA. 



No. 222. Pleurotoma reticulosa. F. E. Edwards. Tab. XXXII, fig. 4, a, b. 



P. testa elongato-fusiformi, undique concentrice line at a : spird acuminata: anfractibus 

 convexis, ad humeros sub-angulatis et tceniold depressd, obsolete curvo-plicald et sulco spirali 

 angusto exaratd, cinctis ; postice concavis, adsuturam marginatis ; tdtimo anfractu in cana- 

 lem latum brevem, antice refexum, producto ; lineis concenlricis supra margines et humeros 

 anfractuum confertis, tenuibus; caterum fortibus, sub-distantibus, irregidaribus; omnino lineis 

 incrementi asperatis : aperturd oblongo-ovali } labro arcuato, acuto, ad humerum sinuato; 

 sinu latiusculo, pro/undo, sub-trigono. 



Shell elongated, fusiform, having the whole surface covered with spiral, raised 

 lines ; spire pointed, produced, nearly equalling the aperture in length. The whorls, 

 six or seven in number, are convex and bluntly angulated at the shoulders, which 

 present a depressed, narrow, ribbon-like band, bearing a series of rather closely set, 

 faint, crescent-shaped plications, formed by the successive rounded extremities of the 

 sinus, and which are divided along the middle by a narrow but perspicuous furrow ; 

 the posterior margins are slightly concave, and bordered round the sutural edge by a 

 coarse, elevated line ; the last whorl is produced in front into a short, very wide, and 

 slightly curved canal, the anterior extremity of which is bent a little backwards. The 

 concentric lines are numerous and irregular, slender, and rather closely set over the 

 margins and shoulders, but distant, thread-like, and much elevated over the middle 

 and front parts of the whorls ; and they are decussated by the perspicuous lines 

 of growth, whence the surface has somewhat the appearance of being covered 

 with fine network. The aperture is of a lengthened, oval form ; the outer lip arched, 

 thin, sharp at the edge, and smooth within ; the sinus, which is placed at the shoulder, 

 is rather wide, deep, and somewhat triangular in form, with a rounded extremity; 

 and the columella is nearly straight, and presents a small crest in front. 



In the general character of the ornamentation this Pleurotoma resembles P. 

 conifera ; but the lineation is of a rougher and more decided character ; the shell 

 itself is wider, the spire relatively shorter, the whorls more convex, the anterior canal 

 shorter and wider, and the sinus not so deep nor so narrow. These differences strike 

 the eye at once on comparing the two ; and as the present shell occurs in a newer 

 and distinct formation, I have retained it as a distinct species. 



From P. crenata (Nyst), with which it also presents a close analogy, it is separable 

 by the wider and more concave margins, and the crenulated and tuberculated shoul- 

 ders of the whorls in that species. 



Size. — Axis, 1 inch and 1-1 2th ; diameter, 5-12ths of an inch. 



Locality. — Barton, where it is rare. 



