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EOCENE MOLLUSCA. 



Specimens occur, constituting a local variety, in which the ribs are more distant 

 and prominent, and extend to the very front of the shell ; four or five distant, elevated, 

 concentric lines cross the whorl over the anterior canal, and are granulated at the 

 points where they are intersected by the lengthened ribs ; elsewhere the whorls 

 are smooth. 



A miocene shell, described by Brocchi (Murex reticulatus — Pleur. ramosa, Bast.), 

 presents a very close analogy with this Pleurotoma, as well in the general shape as in 

 the character of the ornamentation ; it is distinguishable, however, by the greater size 

 of the shell, which attains a length of nearly three inches, the greater narrowness 

 and the simple margins of the whorls, the relatively longer spire and shorter aperture, 

 the shape and position of the sinus, and the condition of the outer lip, which is 

 smooth within. A Pleurotoma also occurs in the nummulitic beds near Pau, 

 described by Rouault (Pleur. Tallavignesii) , to which I have referred some shells from 

 Nuneham and Southend, and which, in the young state particularly, much resembles 

 the present species ; but in that shell the whorls are more contracted in front ; the 

 posterior margins spirally lined, wider, and not so depressed ; the longitudinal 

 plications are more oblique, the lineation finer and more close ; the anterior canal 

 longer ; the outer lip more arched ; and the sinus not so deep. 



Size. — Axis, 10-12ths of an inch nearly; diameter, rather more than 3-12ths 

 of an inch. 



Localities. — Branishaw, for the type ; Brockenhurst, for the variety. 



No. 180. Pleurotoma brevirostrum. Sow. Tab. XXIX, fig. 6, a, b. 



Pleurotoma brevirostrum. Sow. 1823. Min. Con., vol. iv, p. 120, t. 387, fig. 2. 



— — Bionn. 1848. Index Palaeont., p. 1002. 



— — D'Orb. 1852. Prodrome de Paleont., 25 e Etage, No. 41 1. 

 Nec Pleurotoma brevirostrum. Sism. 184". Syn. Meth. Anim. Invert. Pedem. foss., p. 32. 

 nec — — Bell. 1847. Pleurot. Foss. del Piera. (Mem. R. Accad. delle 



Sc. di Torino), p. 607, t. 4, fig. 9. 

 nec — — Naumann. 1853. Atlas zu sein. Lehrb. der Geogn., t. 70, 



fig. 4. 



P. testa elongate!, angustd, turritd, longitudinaliter nodo-costa/d, concentrice lineatd : 

 spird elevatd, acuminata: anfractibus medio angulatis ; marginibus posticis latis, declivis, 

 vix cavatis, sub-lcevibus, ad suturam incrassatis ; ultimo anfractu brevi, antice coarc/ato ; 

 costis crassiusculis, brevibus ; lincis concentricis filiformibus, sub-regularibus : aperturd 

 obovald, in canali brevi, viediocriter lafo, leviter arcuato et retrorsum rejlexo exeunti ; 

 sinu lafo, pro/undo, subtrigono, media in margins collocato. 



Shell narrow, elongate, turreted, longitudinally ribbed, and spirally lined : the 

 spire, which consists of nine volutions exclusive of the pullus, is pointed and much 

 elevated, forming nearly two thirds of the entire shell. The whorls are sharply 



