TYMPANOTONOS. 



Plate I. 



Genus TYMPANOTONOS, Lamarck. 



Testa Jluviatilis, turrita, irregulariier varicosa, longitudi- 

 naliter pUcata, transverse sulcata, pleriimque nodifera; 

 aperturd siibquadratd, coltiiiielld brevi, tortud, canali 

 brevi, emarginato, labro antice producto, sinuato ; 

 opercido corneo, imdtispirali. 



Shell fluviatile, turreted, irregularly varicose, longitudi- 

 nally plaited, transversely sulcated, generally nodi- 

 ferous ; aperture somewliai square, columella short, 

 tortuous, canal short, emarginate, outer lip produced 

 in front, sinuous ; operculum horny, multispiral. 



Our descriptions of the family of CeritJdada having been 

 commenced with a separation of the genera Vertagus and 

 Cerithinm, it has become necessary, if only for the sake of 

 consistency, to follow out the plan of similar divisions 

 among the more fluviatile species. The aperture is pecu- 

 liarly formed in the shells of this genus, the outer lip being 

 much expanded above and below, and brought round pro- 

 minently in front of the canal. The shells are found in 

 marshy places, generally near the mouths of rivers, where 

 the water is brackish ; the older forms in West Africa 

 and India, and the comparatively recent ones in the Philip- 

 pines, collected by the late Mr. Cuming. 



Species 1. (Mus. Cuming.) 



TYMPANOTONOS RETIFERA. Tgm. testd pyramidali, mii- 

 varicosd, curtd, solidd, fasciatd, plicis longitudinaU- 

 biis et sulcis spiralibus, 7wdoso-reticulatd ; anfractibus 

 curiis, supra prope suturam albis tumidis ; aperturd 

 i/itus fused, labro superne et infra expanso. 



The netted Tympanotonos. Shell pyramidal, with a 

 single varix, short, solid, banded, nodosely reticulated, 

 with longitudinal plaits and spiral grooves ; whorls 

 short, white, and tumid above near the suture ; aper- 

 ture brown within, outer lip expanded above and 

 below. 



A. Adams, Sowerby's Thesaurus, Cerithium, sp. 184. 



Hab. Island of Siquijor, Philippines, in salt marshes; 

 H. Cuming. 



Differing from T. fluviatile principally in the suture not 

 being grooved, and in the reticulated sculpture. 



Species 3. (Fig. a, b, Mus. Cuming.) 



Tympanotonos Layahdi. Tgm. testa brevlusculd, tur- 

 rita, ca ruled ; anfractibus rectis, gradatis, unifascia- 

 tis, triseriatim noduUferis, nodulis aqualibus, rotundis; 

 aperturd suiquadratd, iidus fused, labro vix expanso, 

 canali parvo. 



Layard's Tympanotonos. Shell rather short, turreted, 

 bluish ; whorls straight, gradated, single-banded, with 

 three series of nodules, nodules equal, rounded ; aper- 

 ture rather square, brown within, the outer lip slightly 

 expanded. 



A. Adams, Sowerby's Thesaurus, Cerithium, sp. 151. f. 

 257. 



Hab. Ceylon; A. L. Layard. 



The straight, gradated whorls, and the rounded nodules 

 of the surface in this shell distinguish it sufficiently from 

 the other species. 



Species 3. (Mus. Cuming.) 



Tympanotonos fuscattjs. Tgm. testd pgramidali, so- 

 lidd, medio anfractuum tuberculatd, tuberculis mag- 

 nis, extantibus, acutis ; anfractibus supra, et infra ad 

 suturam moniUferd, ultimo bicarinato, infra spiralder 

 striata, labro expanso, antice valide producto, epider- 

 mide crasso,fusco. 



The brown Tympanotonos. Shell pyramidal, solid, 

 tuberculated in the middle of the whorls, tubercles 

 large, standing out, sharp ; whorls beaded above and 

 below at the suture, the last bicarinated, spirally 

 striated beneath, outer lip expanded, much produced 

 in front, epidermis thick, brown. 



LiNN^ns, Systema Natura3 (Murex). 

 Ceritldum ■muricatum, Bruguiore. 



Uab. West Africa, in mouths of rivers. 



This well-known aculeated shell, as well as the follow- 

 ing two species, approach nearly in character to some of the 

 MelaniadcB. These last however, have an oval, paucispiral 

 operculum, while the opercula of Tijmpanotonos is, like 

 other freshwater Cerithiada, multispiral. 



May, 1866. 



