MESALIA 



Plate I. 



Genus Mesalia, Gray. 

 Testa acnminato-turrita, basi roiimdata, colimelld plano-con- 



tortd, recedente, apertura margine infra columellani 



leviter sinuato ei reflexo. 

 Shell acuminately turreted, rounded at the base, columella 



flatly twisted, receding, margin of the apertm-e below 



the columella sinuated and reflected. 

 The flattened receding structure of the columella of the 

 well-known Senegal Turritella (T. brevialis, Lamarck), 

 Le Mesal of Adanson, uiduced Mr. Gray to found a genus 

 for its reception with the name Mesalia, which it is 

 desirable should be adopted. 



It is materially distinguished in this respect from the rest 

 of the Turritella, excepting the little Greenland T. lactea 

 of MoUer, also a Mesalia ; and to these may be added 

 a species {M. Melanioides) from the Cumingian collection, 

 in which the typical character of the genus is yet more 

 strongly developed, and which Jlr. Cuming had abeady 

 put aside in his cabinet as a new form. 



Species 1. (Mus. Brit.) 



Mesalia lactea. Mes. testa turritd, anfractibus tredecim, 

 longitudinaUter snli-obUqui et obese pUcato-costatis, 

 liueis impressis inter castas, lira augustd iiiferne funi- 

 culatis, aperturd parvd ; opaco-albd. 



The milk-white Mesalia. Shell turreted, whorls 

 thirteen in number, longitudinally rather obliquely 

 and stoutly pUcately ribbed, with impressed lines in 

 the interstices, corded round the lower part with a 

 narrow ridge, aperture small ; opake-white. 



Turritella lactea, MoUer, Index Moll. Grcenlandise, p. 9. 



Hub. Greenland. 



MoUer describes this shell as being a diaphanous white, 



but the specimens in the British Museum are rather opake. 



Species 2. (Fig. 3 a, b, Mus. Hanley ; and PL V. 



Fig. 16 a,b, of Tm-ritella, Mus. Cuming.) 



Mesalia brevialis. Mes. testa sttbabbreviato-tiirritd, 



crassd, ponderosd, anfractibus quindecim, rotuiidatis, 



supernl obscure canaliculatis, spiraliter qtdnqucUratis, 



liris siiperioribus fortioribus, iiferioribus interdmn ob- 



soletis, iiiterstitiis undique subtilissime et creberrime 



striaiis, columella plano-conlortd, recedente, margine 



Juue, 



mbreflexo ,■ alba, vel ciiiereo-alid, vel sordide olivaced, 

 iiiterdum strigis fuscescentibus indistiucte pallide tinctd. 

 The short Mesalia. Shell somewhat abbreviately 

 tm-reted, thick, ponderous, whorls fifteen in number, 

 rounded, obscurely channelled round the upper part, 

 spirally five-ridged, upper ridges stronger, lower 

 sometimes obsolete, interstices veiy finely and closely 

 striated throughout, columella flatly twisted, receding 

 and a bttlo reflected at the edge ; white, or ashy -white, 

 or dirty olive, sometimes faintly stained with brownish 

 streaks. 

 Tm-ritella brevialis, Lamarck, Anim. sans vert. (Desliayes' 

 edit.) vol. ix. p. 256. 

 Le Mesal, Adanson. 

 Turritella Mesal, Deshayes. 

 Mesalia sulcata. Gray. 

 Eadem var. Turritella varia, Kiener. 

 Eab. West Coast of Africa. 



An extremely variable species in size and general aspect, 

 but always distinctly characterized throughoiit by its one 

 idea of scidpture. Each whorl is encircled by nine thread- 

 like ridges, five of which remain exposed to view ; of these 

 the two uppermost are more prominently developed than 

 the rest and fonn a slight channel. The interstices are 

 sculptured throughout with exceedingly fine, close-set, 

 sharply defined striae. In some specimens the shell is of 

 a dark dirty olive colour and the ridges bgliter, others are 

 of a light stone colour without any distinction of tone in 

 the ridges. Of the smaller varieties one is of a dark lead 

 colom', another snony white and more elongated, with the 

 ridges almost obsolete ; and a thu-d equally white with the 

 ridges like so many fine opake threads. 



Lamarck, when fij'st describing this species according t(i 

 the present system of nomenclatm-e, apparently from a 

 worn specimen, did not recognise in it Le Mesal of Adanson 

 (Voyage en Senegal, p. 159. pi. 10. f. 7); and M. Deshayes 

 was unable to identify Turritella brevialis in his edition 

 of the ' Animaux sans vertebres ' for want of access to the 

 Lamarckian collection, reserved by M. Kiener for the use 

 of his ' Iconographie des coquilles vivantes;' in which work 

 the identification of T. brevialis with Adanson's Mesal 

 has been recently made known. 



Unacquainted with Lamarck's T. brevialis, from his 

 not referring to Adanson's figure, M. Deshayes described 

 Le Mesal anew. It is much to be regretted that the 

 learned editor of the ' Anim. sans vert. ' was not allowed 



