eaheens oe oon ne Ve uly YOM ys 4" cues Yi x S T DEPARTMENT OF MOLLU ZOOLOC A IN THE Gift of: 2 y= ae a) = = =) ew x ae, MUSEUM OF CoM Wve Yes add i oN i A Y ¢ Bh ih he in AA fe eye tuue je Yas SO ed, ery ¥eeyy y \ ys 1 x ‘| NS Ne 4 Nit S pis wee phew 2 se eT hw} RICHARD 1, JOHNSON LIBRA) OF THE DEPARTMENT CF MOLLUSKS IN THE Museum of Comparative Zoology Gift of: RICHARD I. JOHNSON ieee Yor eo Set (ex RICHARD |, JOHNSON Nee 1763 A MONOGRAPH OF THE HOCENE CEPHALOPODA AND UNIVALVES ENGLAND. BY THE LATE CONTINUED BY SEARLES V. WOOD, F.G.S. VOLUME. 1 LONDON: PRINTED FOR THE PALHONTOGRAPHICAL SOCIETY. 1849—1877. vane Oitmaa! 7 iba hi a eS IAEA ES aay PRINTED BY sg, B, ADLARD, BARTHOLORW CLOSE. oe as He A MONOGRAPH THE EOCENE MOLLUSCA, OR DESCRIPTIONS OF SHELLS FROM THE OLDER TERTIARIES OF ENGLAND. BY FREDERIC E. EDWARDS. PART I. CEPHALOPODA. BF 22.57 B } } I A (le 7 7 ee) LONDON : PRINTED FOR THE PALZONTOGRAPHICAL SOCIETY. 1849, ; — SE OL Mave PRD A = PTH AN LUO LO A re, A MONOGRAPH THE EOCENE MOLLUSC, OR DESCRIPTIONS OF SHELLS FROM THE OLDER TERTIARIES OF ENGLAND. BY FREDERIC E. EDWARDS. PART II. PULMONATA. LA - Shea , A IN —-(L0 : JEs . we xy | ; A \\ \ y . LONDON : PRINTED FOR THE PALASONTOGRAPHICAL SOCIETY. 1852. ~ Viens tee : J . > ie sea ig Man » : iy i, 2 - 2 ae Ab r a mi 7 * D his ( i , ile wing 5 ~~ > = > Al | ti Ui - rh 7 . iy tee SP avn i ce wee Regs a porcitta Aa ne Pay oe | UES Ui OO Wi rr AG 5 eye ae Bees A MONOGRAPH OF THE EOCENE MOLLUSCA, OK DESCRIPTIONS OF SHELLS FROM THE OLDER TERTIARIES OF ENGLAND. BY FREDERIC E. EDWARDS. ry aT PART: Wie 70-14) PROSOBRANCHIATA. Kae , ae GALE IBC FAUT = RRM i “ve ( LONDON : PRINTED FOR THE PALHONTOGRAPHICAL SOCIETY 1854. " s ~ ; Mo aH = - a - iA ee a = “ Nyt y) Saini! moa a ema F vee ie i y a Se a ee ae Seek 1s Gv BLINN au i PLES a iam Vi OD PacaricMermel cia) imran : ae ae ATATHOVAREORON4 a pe ens 7 GA vA =~) ; sO ri Oh eaicters RICHARD 1. JOHNSON A MONOGRAPH OF THE EOCENE MOLLUSCA, DESCRIPTIONS OF SHELLS FROM THE OLDER TERTIARIES OF ENGLAND. BY FREDERIC E. EDWARDS. PAR) DLE. No: Tt: PROSOBRANCHIATA (CONTINUED). oD P07 A} s a (ZA Ml — Ad 44 xxii — xxvi7 p. LONDON: PRINTED FOR THE PALZOONTOGRAPHICAL SOCIETY. 1856. “tna Aviirrait MoI Mute Tor AULAKOOEAD ] A ; i) ' im” jae VO AWwa. oF SDH . Wiwh Ctl wn het RVATHOVARAOF OR ; rip yea ba Nie. Far tale 1 , ‘ PRINTED BY J. E. ADLARD, BARTHOLOMEW CLOSE. . $ = aut fat ie S$ 9b a A MONOGRAPH OF THE EOCENE MOLLUSCA, OR, DESCRIPTIONS OF SHELLS FROM THE OLDER TERTIARIES OF ENGLAND. BY THE LATE FREDERIC E. EDWARDS, F.G:S. CONTINUED BY SEARLES V. WOOD, F.G:S. PART IV. PULMONATA AND PROSOBRANCHIATA. (INDEX TO VOLUME I AND DIRECTIONS FOR BINDING.) Faces 33160; Pirate XXXIV. Vif EG LONDON: PRINTED FOR THE PALHONTOGRAPHICAL SOCIETY. 1877. a ral Wea wa ane ‘g t Le ‘ wt : | j ; a Ee, : _ : = ; a “ai hs 0 Bar Sy, : 4% . a F : ' \ 4 } j ai , \j ag BY nis Z wi . . , : | = PRINTED BY Tr | J. E. ADLARD, BARTHOLOMEW CLOSE. gah “1 Lease fet wl. (eee ) Go the Subscribers, Snorty after the publication of the first part of the Monograph of the Eocene Mollusca, I received a note from Professor Owen, from which the following is an extract :— “In reference to the theory of the siphon of the Nautilus, which you attribute to Mr. Wood, I know you will excuse my referring you to a passage (p. 331) of my Lectures on Invertebrata, in which that theory or function of the siphon is plainly though briefly laid down, and I am sure that our excellent Treasurer would be the last person to claim the exclusive credit of the idea, unless his right to it was based on a publication of it prior to 1843. The scrupulous care which characterises your reference to authorities, assures me that if you have overlooked the passage in my Lectures you will be glad to be referred to it.” Although I had derived much pleasure and instruction from Professor Owen’s admirable Lectures, I must confess that the passage referred to had escaped my recollection; and I greatly regret that this should have been the case, for I should have been glad to have availed myself of the powerful support it affords to the theory I advocated. For the convenience of those Subscribers to whom the Lectures are not immediately accessible, I shall extract the passage to which Professor Owen refers. After noticing Dr. Buckland’s theory of the hydrostatic action of the siphuncle, and the objections against it, the Professor advances the opinions to which I have referred in the ‘ Monograph,’ as to the function of the air- chambers being that of a balloon, and as to the mode in which the animal alters the specific gravity of its shell; and he concludes with the following paragraph,—the one referred to in his letter to me: “Whatever additional advantage the existing Nautilus might derive by the continuation of a vascular, organised, membranous siphon through the air-chambers, in relation to the maintenance of vital harmony between the soft and testaceous parts, such, likewise, must have been enjoyed by the numerous extinct species of the tetrabranchiate Cephalopods, which, like the Nautilus, were lodged in chambered and siphoniferous shells.’ It is due to Professor Owen that I should, to the best of my power, repair my omission to refer to this eminently suggestive passage ; and now, having brought it distinctly before the Subscribers, I leave it to them to decide as to whom the credit of the siphuncular theory in question is due. ine doe aay July, 1852. CORRIGENDA. + Substitute Sconce for Headon Hill, at p. 65, line 24; at p. 70, line 13; and at p. 78, line 15. Fee) al ball. bie 2 e //P60) CONID&. ist .Or, GRNERA, AND. oS PEC LES. Conus, Linn. . 5 Conus antediluvianus, Desh. (nee Brug. nee Lamk. ) concinnus, Sow., t. 24, fig. 13, a—e corculum, Sow. : < deperditus, Brug., t. 25, fig. 2, a—e deperditus, Sow. (non Brug.) diadema, Ldw., t. 24, fig. 8, a—d diversi formis, Se Lamarckii, Hdw., t. 25, fig. 3, a—e pyriformis, Sow. ; . lineatus, Sol., t. 24, fig. 10, a—e scabriculus, Sol., t. 24, fig. 9, a—c velatus, Sow., t. 24, fig. 12 ‘ ConorRBIs, Swains . 6 : Conorbis alatus, Hdw., t. 25, fig. 1, a, 6 dormitor, Sol., t. 24, fig. 11, a—e Pievrotoma, Lamk. : . Srcr. I.—Shells fusiform. A. Sinus in the posterior margin of the whorl. Pleurotoma acuminata, Sow., t. 27, fig. 3,a—d . acuticosta, Myst, t. 28, fig. 14, a—e attenuata, Sow., t. 27, fig. 6, a—e biconus, Hdw., t. 33, fig. 7, a, 6 bracheia, Hdw., t. 29, fig. 9, a, 6 brevirostrum, Sow., t. 29, fig. 6, a, 6 coarctata, Hdw., t. 28, fig. 12, a—e cocciphora, Hdw., t. 26, fig. 2 cochlis, Hdw., t. 33, fig. 6 conica, Hdw., t. 27, fig. 8 . conoides, Sol., t. 33, fig. 5, a, 5 constricta, Hdw., t. 29, fig. 1, a—e . crassa, Edw., t. 26, fig. 1, a—d PAGE 187 194 196 199 191 194 190 190 194 190 199 198 193 202 202 200 203 230 249 237 318 263 258 245 217 272 239 317 256 212 Pleurotoma crassicosta, Hdw., t. 26, - 10, a, curvicosta, Sow. . . cymea, Edw., t. 26, fig. 4, a, b; and t. 27, fig. 9 dentata, Lamk., t. 26, fig. 5 desmia, Hdw., t. 27, fig. 5 dilinum, Hdw., t. 28, fig. 15, a, 6 dissimilis, Hdw., t. 28, fig. 7,a—e . exorta, Sol., t. 26, fig. 12, a, 6 Fisheri, Hdw., t. 31, fig. 14, a, 6 formosa, Charlesw. < fusiformis, Sow., t. 27, fig. 1, a, 6 gomphoidea, Fduw., t. 28, fig. 13, a—f gonicea, Hdw., t. 25, fig. 10 granulata, Lamk., t. 28, fig. 4, ane. Headonensis, Ldw., t. 28, fig. 17, a—e helicoides, Edw., t. 32, fig. 7, a, 6 helix, Edw., t. 25, fig. 7, a, 6 inarata, Sow., t. 25, fig. 6. inflexa, Lamk., t. 28, fig. 3, a—c innexa, Sol., t. 28, fig. 1, a—e Keelei, Hdw., t. 26, fig. 6 . leevigata, Sow., t. 26, fig. 9, a, 6 lanceolata, Hdw., t. 26, fig. 11, a, 6 . Lehonii, Row., t. 31, fig. 13, a, 6 lepta, Hdw., t. 28, fig. 10, a—e lissa, Hdw., t. 28, fig. 5, a, 6 macilenta, Sol., t. 26, fig. 13, a, 6 macrura, Hdw., t. 33, fig. 8, a, 6 microcheila, Hdw., t. 28, fig. 8, a—f microdonta, Hdw., t. 27, fig. 4 nodosaria, Edw., t. 29, fig. 8, a, b . nodulosa, Lamk., t. 29, fig. 7, a—c . planetica, Ldw., t. 26, fig. 3 ee yA CONIDA—LIST OF GENERA AND SPECIES. PAGE PAGE Pleurotoma plicata, Lamk., t. 28, fig. 11, a—e 248 Pleurotoma gentilis, Sow., t. 30, fig. 1, a—e 280 pupa, Hdw., t. 28, fig. 9, a—e 253 granata, Hdw., t. 31, fig. 7, a—e - 308 pyrgota, Hdw., t. 28, fig. 16, a—e 257 Hantoniensis, Hdw,, t.31, fig.8, a—e 315 pyrulata, Desh., t. 27, fig. 7, a, 6 232 hemileia, Edw., t. 32, fig. 13, a, 6 314 rostrata, Sol., t. 26, fig. 8, a—e 218 insignis, Edw., t. 32, fig. 14, a, 6 301 scabriuscula, Hdw., t. 29, 2,a—ce 254 Koninckii, Wyst, t. 29, fig..15, a, & . 279 semicolon, Sow. = AD leviuscula, Hdw., t. 32, fig. 9, 4,6 . 310 sindonata, Hdw., t. 29, ro 12,.4,6 . 263 ligata, Ldw., t. 32, fig. 12, a, b ey Sie? stena, Edw., t. 25, fig. 4, a, b 207 lima, Hdw%, t. 32, fig. 3, a—e - 296 subula, Hdw., t. 29, fig. 13, a, 6 267 mixta, Ydw., t. 30, fig. 5, a, 6 » (277 sulculosa, Hdw., t. 27, fig. 2, a—e 229 monerma, Edw., t. 32, fig. 1, a—e 292 symmetrica, Edw., t. 25, fig. 5, a, 6. 209 obscurata, Sow., t. 31, fig. 1, a, & 296 Tallavignesii, Row., t. 33, fig. 9. a,b. 270 parilis, Edw., t. 31, fig. 10,a—e . 309 terebralis, Lamk., t. 27, fig. 10, a—k 233 plebeia, Sow. 286 tereticosta, Hdw., t. 29, fig. 5,a—d . 250 Prestwichir, Edw., t. 30, fig. 3, we 282 teretrium, Hdw., t. 25, fig. 8 a—h 210 puella, Zdw., t. 31, fig. 15, a, 6 305 textiliosa, Desh., t. 26, fig. 7 222 pupoides, Edw., t. 32, fig. 11, a, 6 302 transversaria, Lamk., t. 25, fig.9,a,6 214 reticulosa, Hdw., t. 32, fig. 4, a, 6 298 transversaria, Sow. (non Lamk.) 213 rotella, Hdw., t. 31, fig. 4, a, 6 299 tricincta, Hdw., t. 28, fig. 6, a, b 252 rotundata, Hdw., t. 31, fig. 9, 4,6 . 307 turgidula, Edw., t. 29, fig. 4, a—e 251 scalarata, Edw., t.31, fig. 6,a,6 . 295 turpis, Hdw., t. 28, fig. 2, a—e = 3207) Selysii, De Hon., t. 29, fig. 17, a—d. 278 turrella, Morr. Cat. (non Lamk.) . 319 simillima, Edw., t. 30, fig. 4, a—e 283 undata, Lamk., t. 29, fig. 11, a, 6 261 teeniolata, Hdw., t. 30, fig. 13, a—e. 284 verticillum, Hdw., t. 29; fig. 3, a—e. 255 turbida, So/., t. 32, fig. 2, a—e 311 vicina, Hdw., t. 29, fig. 10, a, 6 . 266 yarians, Hdw., t. 31, fig. 12,a,6 . 293 Sct. 1.—Shells fusiform (continued). Leia pn Eee: ie ; 208 z. Sinus. on the shoulder of the whorl. Nolgent; PAst.,\t-130; tig alga eae = Waterkeynii, Nyst, t. 30, fig. 8, a—e 275 Pleurotoma abnormis, Hdw., t. 30, fig. 14, a,b . 294 Wetherellii, Hdw., t. 29, fig. 16, a—d 285 acutisinuata, Hdw., t. 32, fig.5, a,b. 306 Woodii, Edw., t. 32, fig. 10, a,6 . 304 aspera, Edw., t. 29, fig. 14, a, 6 Oh} zeta, Hdw., t. 31, fig. 16 - 284 callifera, Bdw., t. 30, figs: 9,10,11, 4,5 291 zonulata, Hdw., t. 32, fig.6,a,6 . 317 eataphracta, Morr. Cat. lst Edit. (non Broee.) . : . 311 Sect. I].—Shells coniform. cedilla, Hdw., t..31, fig. 5, a, 6 - 300 Pleurotoma-amphiconus, Sow., t. 33, fig. 2, a, 6. 322 colon, Sow. . = 311 ‘clavicularis, Lamk. = 320 comma, Sow., t. 30, fig. 2. 281 glabrata, Lamk., t. 33, fig. 4 . 324 conifera, Edw., t. 31, fig. 3, a,.6 274 prisca, Sol., t. 33, fig. 1, a—e . 320 crebrilinea, Hdw., t. 30, fig: 6, ae. 290 semistriata, Desh., t.33, fig.3, a,6 . 323 curta, Hdw., t. 31, fig. 2, a, 6 + 805 | Borsonta, Bell. 4 ; o. o20 denticula, Basé., t. 30, fig. 7, a—h . 286 Borsonia Biaritzana, Row., t. 33, fig. 11, a, 6 + OLE divisa, Edw., t. 31, fig. 17, a, 6 ens lineata, Hdw., t..33, fig. 14, a, 6 5 Sk) fasciolata, Hdw., t. 30, fig. 12, a,6 . 286 semicostata, Hdw., t. 33, fig. 13, a, . 329 flexuosa, Munst., t. 32, fig, 8,a—e . 302 sulcata, Hdw., t. 33, fig. 12, a, 6 > 025 J// PREFACE. Owrne to failing health Mr. F. E. Edwards was unable to continue his Monograph of the Eocene Gasteropoda after the year 1860, but with the facilities afforded by specimens from his Cabinet I was enabled to produce some instalments of the Monograph of the Bivalvia in the years 1864 and 1871. Mr. Edwards’ death took place in 1875, and terminated the possibility of any further prosecution of the work by him, his Collection having gone to the British Museum some years previously. I essayed, how- ever, to make some progress with both portions of the work, and the solitary Plate of the Gasteropoda now given was in consequence engraved. I found, however, that owing to advanced years and other circumstances I was unable to carry out my wish, and have been compelled to relinquish it with the solitary Plate referred to. SEARLES V. WOOD. Isr NovemeBer, 1876. b ot hel = 6 7 ey ceo, shh a ae eM hrs ahs ey = MPs oy rel baci alin ial! wee hae, ATK wat 60 “i bi : aut i 4 * hs fa “i ute | Wilt (aillyin fal/airs ‘ihe eis Wa still ee anilig die ‘afta ay wer vary Lew PATA et Cay oa ait oft nt ae af Au ssh Be (nal Vie Pinte nt can he pial rs it i hil ia ine 1 ue “a ¥) t oa LS ie ea "I ij an areas ae ri / tig Rviy POI al mw a bi Nia: | a) y | ; $s ae ; ’ } vi i ae f . ; BS ] oral. P| = ct a og hans - F piieaiae Dea ed: . ss yen et Tet? Sa eae A I = pe a Fis San a ee miro Ay : (tse ry Hg _ en i cL Tee Sah Le Seva ees APS | ay, wee? 5 lye, Vie nee? BiG” Oreo Aye MEN ily, Seow 7 oi VAy) Sal es Fe o§ via. ie gg, ae ay ta ele Die Vy igh oles oom” Me SO Pe ee ai een 5 a —) Maa y rte ' a a TAREE don fe ree ae et)’ eee Wl a BY) a Re tae KA EAS. rd A Oe a no) g*. PT hl! was lt Oe > : 4 de ~~. TY genic? ; i ' nit vhs iP ality Sexy y a a erper 8 onveiy Te | ier a Sah hel} i ae they jah > ‘ ee Wad a4 ths) ie é ' | 4 ‘ ¥ = uhyy) TT a. A t U CORRIGENDA. Page 65, line 24, substitute “ Sconce” for “ Headon Hill.” ” ” 70 78 ” ” 13 ” ” 15 . ie ” 2 ” ”? In the head-lines to sheets 17, 18, and 19 (p. 129 e¢ seq.), for “ Pulmonata”’ read “ Prosobranchiata.”’ Page 126, line 10, for ‘‘ Cypraea” read “‘ Cypreee.” 14, for “figs. 3 a—d”’ read “ figs. 4 a—e.” 27, for * Basiugstoke”’ read “Cuffel, near Basingstoke.”’ 28, for “(t. 25)” read “ (t. 5).” 30, after the word “size” insert “axis 1 in. and +4,ths; 133 134 155 155 158 ” ? 14, for “figs. 4 a—e ” read “figs. 4 a—d.” 160, last line but one, after “axis” insert ‘‘2 inches nearly,” Oe co bo iS wmnwnwnd Ww ies) 290 295 300, last line, add “ Highceliff.” and 54th.” , line 33, for “figs. 2 a—b” read “figs. 3 a—b.” 3 from bottom, add ‘‘ Nuneham”’ to the list of localities. ” ” 13, dele ‘* Barton.”’ last line, add “ Brook.” rst line, for “fig. 13 a, 6” read “fig. 15 a, 6.” , line 25, for ‘‘ Hampstead Railway Tunnel’’ substitute “ Potter’s Bar.” , last line, add “‘ Highgate, Potter’s Bar, and Southampton.” , line 17, add “ Hornsey.” +} ” 16, for ‘‘ fig. 8 a—e” 8, add “ Highgate.” read “fig. 6 a—e.” diameter -°,ths of an inch.” and after “diameter” insert “1 in, Aas | 4 ae oe NT Au ae ar ah ie , AY: ee ae os as | Ja i. . » - 7 ; . a, MT PAOTTONS, co a on eee ee 0 m4 qe! fin jn yi WIR Bai at Vrdy EYiolagitanvley a eee wa 4 a es = ee | Le i eu . =< 1 r 7 ut { . a : i a os ee are eae Wi fi hy | a) z ia? tee \- reel i Aa) | "4 oun ; val) val Ry Li 2 ata f ' " ; tLe LAY ie st ey gipie. A 10 depen dh Bi! did) ¢ ry Priel tai eel lobe Oh) it green) ) ta! M tsa , 4 PAL ire . ‘ potit ie) ¥ Sn a mh ROE | 7 a ih : Te Diduy fii 1 hiss j\ As aL ah th i iN ; rae [ j iti A at 1 aake : ' 7 om { Gut : " rf a) "hele 7 iy i fi res ; A awa iets ’ i+) > 7 ; j r : q if (). deka Cc ee | ik jabs ole 4 as f - , J ‘ je elit a jays! ; , ’ = =a i i ; > 1.4 ie ; SU » 5 m 7 = ai% » ‘ ‘ } Y / / if THE KOCENE CEPHALOPODA AND UNIVALVES. DIRECTIONS TO THE BINDER. The Monograph on the Eocene Mollusca (Cephalopoda and Univalvia) will be found in the publications of the Paleeontographical Society issued for the years 1848, 1852, 1854, 1855, 1858, and 1877. Cancel the title-pages affixed to the separate parts in the volumes for the years 1848, 1852, 1854, Lee: oe 1855, 1858, and 1877, and substitute that provided in the volume for 1877. Cancel also the corrigenda NE printed on slips in the volumes for the years(1852, 1854, 1855, and 1858, and substitute that provided in SWAIN the volume for 1877. Cancel in addition the “List of Conide” (following page 330) printed in the Ho. volume for 1858; and let the order of binding be—(1) New title-page to the complete Monograph (in 1877 vol.) ; (2) Preface (in 1877 vol.) ; }—-Netice to Sabsertbers{(sheet-7*im 1852 vol) ; (4) Corrigenda Gee. (in vol. for 1877) ; (5) Pages 1—361; and (6) Plates I—XXXIV. —ORDER—OF BRBPRG AND DATES OF PUBLICATION. PAGES PLATES | ISSUED IN VOL. FOR YEAR PUBLISHED =< —s = wn | Title-pagea! — 1877 February, 1877 SAN = —>¥ Preface = 1877 | ¥ jes otice to Subscribers -- | 1852 | August, 1852 : Corrigenda | = 1877 February, 1877 frbeinn z 1— 56 I—IX | 1848 July, 1849 57—120 X—XV 1852 August, 1852 121—180 XVI—XXIII 1854 May, 1855 181—240 | XXIV—XXVII | 1855 February, 1857 241—330 XXVITI—XXXIII 1858 | March, 1861 331—361 XXXIV 1877 | February, 1877 LE ae ee ag awa A — , Wai“ a ete —= d, 4 Io pes feud X fag = i (g7en4 LP £ 4 letercter, oleieAtms [lila tes : LL if af Zi LL 7f) 2s EE = ftot TL. CA lei nen -/ VY _L—IG . 0A: f=/& }: Gd £ Gi A MONOGRAPH OF THE MOLLUSCA FROM THE EOCENE FORMATIONS OF ENGLAND. FIRST CLASS—CHPHALOPODA. CvuviEr. Mo.uvusca BracuiaTa. Poli. Cfpuatoropes. Lamarck; Férussac. CépHatopHores. De Blainville. THE Cephalopoda form the first class of Molluscous Animals in the system proposed by Cuvier, and consist of the several encephalous mollusca whose organs of reptation are attached to the head. Possessing an organization more complicated and more fully developed than that of the other molluscs, they have a higher rank in the scale of existence. In a descending series they immediately succeed the Vertebrata. It is in this class that the latest indication of an internal skeleton will be found. Among the more highly organized of the Cephalopods, the cephalic ganglia, to which, from their importance and development, the term drain may still be applied, are surrounded and protected by a cartilaginous process, called the cranial cartilage, analogous with the cranium of a vertebrate animal, and in which the muscles of the arms and tentacula are inserted. Other cartilages, subservient to the muscles of the funnel and of the fins, where those organs exist, will be found in other parts of the body, and may be said to represent, in rudiment, those portions of the skeleton which in the vertebrate animals sustain their locomotive organs. The Cephalopods are eminently social animals; they are all predatory and voracious in the extreme, and appear to be nocturnal or crepuscular in their habits. Some, the more highly organized, inhabit the deep seas only; others frequent the coasts or shallow seas, or conceal themselves in holes in the rocks. M. d’Orbigny, to whose recent work entitled ‘Mollusques vivants et fossiles’ I am largely indebted, shows that to these various habits the zoological peculiarities of the different genera are referable ; and he distinguishes the animals as pelagic (pelagiens), or littoral (cOtiers), according to the fact of their frequenting the deep sea or the coasts. The Cephalopoda have a distinct head, surrounded by arms or tentacula; they possess organs of sight and hearing, closely resembling those of vertebrate animals, 1: 2 EOCENE MOLLUSCA. and they are endowed with the sense of smell. The eyes are placed on the sides of the head, and in one of the two orders into which the animals are divided (the Dibran- chiata) are, generally, lodged in an orbital cavity in which they move freely ; in some genera, however, they are united to the outer integument, and are then incapable of motion. When lodged in orbital cavities, they exhibit two distinct modifications, of which M. d’Orbigny has availed himself for the subdivision of the order into two groups (called respectively J/yopside* and Ovgopsidet). In the first modification, which is found among the littoral Cephalopods, the eyes are wholly covered by the skin of the head, which becomes thin where it passes over the ball of the eye; in the other modification, which characterises the pelagic species, the orbital cavity is largely open, and the eyes are in contact with the water. In the tetrabranchiate Cephalopod, whose food is found principally at the bottom of the sea, and to whom enlarged vision would be comparatively useless, the eye is not lodged in an orbital cavity, but pedicillated, and assumes a simpler structure, approaching that of the inferior mollusc. These animals possess an external auditory opening, generally protected by an external ear more or less complicated in structure. The organs of smell are supposed to reside in certain pores or sacs, opening externally, termed by M. dOrbigny aquiferous pores (ouvertures aquiferes), which are divided into cephalic, oral, anal, and brachial pores according to their position, and are used by him as generic distinctions. The mouth is terminal, and is furnished with two strong, horny beaks or jaws termed mandibles, working vertically upon each other like the bill of a parrot, with which they are usually compared. The body is inclosed in a thick membranous skin or mantle, united along the belly of the animal so as to form a muscular bag or sac, open at the upper extremity, and containing the branchial apparatus and viscera. In its general shape it is round, or more or less elongated, and cylindrical or depressed. To this body, distinguished as the posterior portion of the animal, the anterior or cephalic portion, consisting of the head and the arms or tentacula it sustains, is attached by one or more ligaments, some internal, others formed by the continuation of the skin of the body, and termed cervical or lateral ligaments, according to their position. The condition of these ligaments varies with the habits of the animal, and upon it generic characters are founded. They attain their greatest strength in the littoral Cephalopods, and in some genera afford a sufficient attachment between the head and the body; but in the Cephalopods more or less pelagic, in which the free and independent use of the organs of prehension, and a simultaneous active exercise of the bodily locomotive function, would be materially impeded by an extensive permanent attachment, the ligaments are considerably reduced; so much so, in fact, that they would afford a very imperfect * Myopside ; from pvw claudo, oxis visus. Oigopside ; from évyw aperio, ois visus. 5 3 ¥: 2 CEPHALOPODA. 3 guard against the resistance caused by the rapid motion through the water of a mass so large as the cephalic portion of the animal. To obviate this defect, a peculiar apparatus is found in various Cephalopods, which, capable of bemg instantly brought into action, provides an additional and firm attachment of the head to the body. This apparatus is variable in form, and, except in three genera in which it is not found, forms one of the most certain generic characters. It consists of one or more cartilaginous or fleshy protuberances, placed on each side either of the inner surface of the body or of the base of the head, which fit ito corresponding holes or depressions formed for their reception in the opposite part of the head or body. This apparatus, termed by M. d’Orbigny the apparatus of resistance (l'appareil de resistance), has relation to the swimming power of the animal, and is more or less complicated as that increases or diminishes. The respiratory apparatus consists of two or four lamelliferous branchieze or gills, lodged in chambers contained in the visceral sac, but separated from the viscera by a membranous partition. The number of these gills has been adopted by Professor Owen as an ordinal distinction ; and, in the system of classification proposed by him, to which I shall hereafter refer, the Cephalopods are divided into dibranchiate and tetra- branchiate orders according to the fact of their possessing two or four branchie. Into the chambers containing the gills, the water is freely admitted by a valvular aperture, and having served the purpose of respiration, flows, or is forcibly ejected by the muscular contraction of the body, through the excretory tube or funnel (¢”/undibulum). The water thus expelled in streams more or less powerful and frequently repeated, at the will of the animal, causes a retrogressive movement, which forms its principal mode of locomotion, from which circumstance the tube itself is called by M. d’Orbigny the locomotive tube. The body thus becomes the most important locomotive agent ; and as its size and shape must materially influence the retrogressive motion, we can readily conceive that they will have relation to the exigencies of the animal for swimming. Thus the pelagic species, in which the body, from its comparative size, and its cylindrical form and tapering extremity, is adapted to contain a large quantity of water, and to move through the sea with facility, are, as their necessities would require, pre-eminently powerful swimmers; while, on the other hand, in the littoral species, to which great retrogressive power would be not only unnecessary, but a source of frequent injury, the body is small and rounded, or depressed, so as to afford a broad surface on which the animal can rest upon the ground. Among the dibranchiate Cephalopods the circulation is performed by the agency of a central or systemic heart, of two lateral hearts, subservient to the propulsion of the blood through the branchie, and thence called the dranchial hearts, and of a venous system consisting of two principal vessels, vere cave, contained in a cavity called by Professor Owen the pericardium, and communicating freely with the branchial chambers, and of other subordinate trunks or vessels. In this cavity terminates the 4 EOCENE MOLLUSCA. tube called the siphon or siphuncle, which perforates and traverses the chambers of all the multilocular shells, whether external or internal,* and by means of which, as it has generally been supposed, the animal can diminish or increase the specific gravity of the shell, and so facilitate its rising or sinking in the water. In the recent WVaztili, the sole living representatives of the tetrabranchiate Cepha- lopods, the lateral hearts are wanting, the enlarged surface of the branchial apparatus rendering such additional means of circulation unnecessary. The funnel or locomotive tube is placed beneath the head, and supports at its base the apparatus for resistance before noticed. Its functions are various: it conveys away the water inhaled for respiration after that object has been served, and, as we have already seen, becomes, at the will of the animal, the principal locomotive agent ; it is also the excretory tube. The condition of this organ is used by Professor Owen as an ordinal character; in the dibranchiate Cephalopods the parietes of the funnel are entire, while in the tetrabranchiate Cephalopods they are disconnected along the ventral margins. A peculiar provision for defence is found among the naked Cephalopods, which is denied to those protected by an external shell; this provision consists of an organ for secreting and expelling an inky fluid, by the effusion of which the animal, when alarmed, is enabled to discolour the surrounding water, and thus to facilitate or conceal its escape. The fluid is contained in a bladder-shaped sac, called the ix/-d/adder, and its presence may be regarded as a certain indication of the dibranchiate type of organization.t In addition to the retrogressive power possessed by all the Cephalopods, and derived from the agency of the funnel, the decapodous genera are provided with lateral or terminal fins, more or less coriaceous, according as the habits of the animal are more or less pelagic or littoral. The motive function of the fins, however, appears to be secondary ;_ those organs being used chiefly to sustain or steady the animal, and direct its course through the water. The position of the fins is used as a generic character. The dibranchiate Cephalopods carry on their heads eight or ten arms, the place of * In M. de Blainyille’s ‘ Mémoire sur 1’Animal de la Spirula et sur |’ Usage du Siphon des Coquilles Polythalames,”’ the siphuncle is described as a solid tendinous prolongation of the retractor muscles, by means of which the animal is enabled to withdraw the cephalic mass within a cavity formed by the anterior extremity of the mantle, and thus to regulate the specific gravity of the body. It appears, however, from Professor Owen’s examination of two specimens of S. Peronii (fragilis), captured and brought home by Captain Sir Edward Belcher (see Zoology of the Voyage of the Samarang), that the soft or membranous siphon is in reality a ¢uée continued from the calcareous siphon and the last chamber of the shell, through a semicircular aperture in the mantle, into the visceral cavity. ; + M. d’Orbigny, after referring to these means of escape in the Sepiz, says (Moll. Viv. et Foss., vol. i, p. 134), that he is far from believing that the faculty is enjoyed by every species; and that, in fact, if it exists among the Sepidee, it is at the least doubtful among the other Cephalopods, who possess but a small quantity of the liquid, which they only expel when dying. CEPHALOPODA. 5 which, in the tetrabranchiate Cephalopod, is supplied by a multitude of tentacula grouped around the mouth. These arms or tentacula are organs as well of locomotion as of touch and prehension. In the dibranchiate Cephalopod the arms are furnished with suckers (acetabula), and are of two kinds, viz.: eight sessi/e arms encircling the mouth, and connected at the bases by a muscular web more or less broad; and two tentacular arms placed one on each side, and capable of considerable extension. The Octopods are furnished with the sessile arms only ; the Decapods possess also the tentacular arms. The development of the sessile arms appears to be in inverse ratio with the retro-swimming power of the animal, and, consequently, as we have before seen, with the size of the body. In the pelagic Decapods, which possess the highest retro-swimming power, and whose body is comparatively large, the arms are short ; while in the finless Octopods and the littoral Decapods, which have small bodies, and are consequently bad swimmers, and whose habits require the means of creeping along the ground, the arms are infinitely larger, and the connecting web is broader, so that they serve also for reptation. The arms, to adapt them more perfectly for prehensile purposes, are provided with suckers placed zz serie, on the inner surface. These are sometimes simple, i. e. unarmed ; but in some genera they are surrounded by a horny dentated hoop, and in others are wncinated, or armed with sharp, horny hooks. When the prey is once seized by this formidable apparatus, escape is hopeless. In the tetrabranchiate Cephalopod, which is always attached to a dense calcareous shell, and whose principa! food appears to be the crustacea or testacea living at the bottom of the sea, the complicated mechanism of the arms entirely disappears, and the animal is provided with numerous, small, retractile tentacles, by which the sense of touch, as necessary to it as enlarged vision is to the dibranchiate Cephalopod, is largely developed. The presence of the sucker bearing arms, or of the tentacula, is an ordinal distinction, and has been adopted by the French naturalists for the designation of the two orders, corresponding with the dibranchiate and tetrabranchiate orders of Professor Owen, into which they have divided the Cephalopods; the armed and unarmed conditions of the suckers are also used as subordinal and generic distinctions, and characters of families and genera are founded upon the retractile power of the tentacular arms. Exclusive of the impulsion derived from the funnel, and the capacity to rise and float in the sea which the chambered and siphoniferous shell affords, the tetrabranchiate Cephalopod can only creep, like the gasteropods, along the bottom of the sea by means of the free and expanded margin of the anterior extremity of the body. The animal whose zoological peculiarities have been thus cursorily noticed, is sometimes lodged in a symmetrical shell, wxi/ocular or camerated (multilocular), that is, presenting a series of chambers divided from each other by thin partitions (septa), and successively added by the animal to meet the exigencies of its increasing bulk, and in 6 EOCENE MOLLUSCA. the last of which the body is contained. The partitions present the greatest variety of form ; being in fact moulded upon the animal, they indicate corresponding zoological peculiarities, and generic distinctions have been founded upon them. Among the Nautilide, one of the families into which the tetrabranchiate Cephalopods are divided, the posterior extremity of the body is round and without any projecting part, or /o4e as it is termed, and the septa therefore are characterised by simple curvatures or undulations, and their margins are always entire; and thus we are led by analogy to believe, that in the C/ymenide the animal had an angular lobe on each side of the body, from which the sinus, which characterizes their septa, would take its form; and that in the Ammonitide the posterior extremity of the body had many lobes, the edges of which were foliated, whence the septa assumed corresponding curvatures with foliated margins. Sometimes, and this is most generally the case among the recent Cephalopods, the animal is without the protection of an external shell; but it is then supplied either with a calcareous chambered shell almost wholly buried in the animal, or with a horny or calcareous substance, simple, or more or less complicated in form and structure, wholly internal, and encysted in the back of the mantle. From the presence or absence of the external shell, the Cephalopods have been, and in fact still are, popularly divided into shell-bearmg and naked Cephalopods, although in the systematic arrangement proposed by Professor Owen these terms have a more restricted application. The chambered shells are characterised by a peculiar apparatus, by means of which, as it has been generally supposed, they are made subservient to hydrostatic purposes, although the precise mode by which that end is attained is merely conjectural. From Professor Owen’s description of the MVautilus Pompilius, it appears that the posterior part of the visceral sac is prolonged in the form of a membranous tube, which, passing through a short calcareous collar, formed in the disc of each septum, and called the fesfaceous siphon, traverses the different chambers to the extreme nucleus of the shell. This tube, with the calcareous collar which, more or less, covers and protects it, is termed the siphon or siphuncle, and is found in all the multilocular shells strictly so called, whether external or internal, recent or fossil ; and its position with reference to the margin of the shell, is used as another distinction between the Ammonitide, the Clymenide, and the Nautilide ; being ventral or external, that is, placed near the outer margin, in the Ammonitide ; central, that is, at or near the middle of the disc of the septum, in the NVautiide ; and dorsal, that is, close to the preceding volution, in the Clymenide. The process by which the external shells of the Cephalopods are constructed does not appear to differ essentially from that used by the inferior molluscs. Professor Owen has described the mode of growth in the Nautilus Pompilius ; and we are led by analogy to the conclusion, that the shells of the extinct Wautili and the Ammonites, and their various cognate genera, were formed in the same way. In the recent - CEPHALOPODA. il Nautilus the animal is attached to the shell by two large lateral muscles, called the adherent muscles, and by a belt or cincture of horny matter, which completely encircles the posterior part of the visceral sac, and expands at the sides into broad dises, which serve as the medium of insertion of the adherent muscles ; and the prolonged posterior extremity of the visceral sac, forming the membranous siphuncle, is a third mode of attachment. As the animal increases in size, the adherent muscles and the cincture gradually advance their line of attachment, and the membranous tube at the same time lengthening in proportion, a cavity is thus formed between the septum and the lower portion of the visceral sac. A deposition of calcareous matter by the surface of the mantle then takes place, commencing at the sides of the shell, and proceeding towards the membranous tube, round which it is continued backward, and forms the calcareous or festaceous siphon. Thus, as the animal increases in bulk, the dwelling-chambers are successively formed and converted into air-chambers, by means of which the specific gravity of the shell and its contents is maintained nearly in equilibrio with that of the surrounding water. During the growth of the animal the anterior portion of the mantle secretes calcareous matter, which it deposits in successive layers on the margin of the aperture; and thus the enlargement of the outer wall of the shell is effected. I must add, that the theory of the gradual advance of the adherent muscles and the cincture during the growth of the animal is opposed to the opinion of M. d’Orbigny, who, in his hypothesis as to the function of the siphuncle, noticed subsequently, maintains in effect, that the advance of the muscles (and, I presume, of the cincture also) is periodic. The Argonaut presents an extraordinary deviation from the general laws which govern all other molluscous animals; inasmuch as the animal, although perfectly free and unattached to the shell it inhabits, is not now considered to be a mere parasite,* * It is foreign to the present purpose to enter into the question as to the parasitism of the Ocythoe ; the experiments of Madame Jeannette Power, confirmed to a great extent by the observations of M. Sander Rang and M. d@’Orbigny, and more recently by those of Mr. Adams, during the voyage of H.M.S. Samarang, are generally considered as removing all doubt as to that animal being the fabricator of the shell in which it is found; and the theory of parasitism is now rejected by nearly all naturalists. A detailed account of the facts ascertained and recorded by Madame Power and M. Rang will be found in M. Rang’s Memoire, published in Guerin’s ‘ Magasin de Zoologie,’ and in Madame Power’s ‘Observations on the Poulpe of the Argonaut,’ translations of which are published in the ‘Mag. Nat. Hist.,’ new series, vols. iii andiv. The observations of Mr. Adams, published in the ‘ Zoology of the Voyage of the Samarang,’ tend to prove that the shell is constructed by the female Argonaut as a nest for receiving her eggs, and protecting them from injury, resembling in some measure the rudimental capsules secreted by many marine Gastropods for the preser- vation of the embryo. The animal firmly retains possession of this light caleareous shell-nest by means of the broad expanded membranes of the posterior pair of tentacles; but when disturbed or captured, she loosens her hold, and leaving her cradle to its fate, swims about independent of her shell. Having once deserted the nest, it appears that she has not the power, or more properly the sagacity, to re-enter it. Numbers of male Argonauts were taken by Mr. Adams, but always without shells. There are, however, in this theory, difficulties which probably future observation may explain. In the first place, the shells SP 8 EOCENE MOLLUSCA. as at first was supposed to be the case, but the actual fabricator of the shell ; and it is believed that the broad membranes usually termed ve/a or velamenta, into which the extremities of the posterior pair of arms are expanded, and which usually envelope the shell, are the organs by which the deposition is effected; the mantle itself, apparently, not being capable of a calcifying secretion. The beaks or mandibles with which the mouths of the Cephalopods are armed, vary in structure according to the habits of the animal. In the dibranchiate Cephalopod, whose principal food consists of fish, the mandibles are sharp, and entirely composed of horn; but, with the tetrabranchiate Cephalopods, the mandibles are blunt, and cased at their extremities with hard calcareous matter, adapted for the crushing of shells, and the defensive coverings of crustacea. The fossil substances called Rhyncolites, resembling the mandibles of the recent Wawtilus, and found associated with the numerous chambered shells so abundant in the secondary and transition forma- tions, appear to be remains of Ammonites, and the other cognate extinct genera by which those shells were inhabited.* That the external chambered shells of the Cephalopods act in the same way as the swimming bladders of fish, and serve as floats, is obvious from the circumstance that, when deserted by the animal, they swim on the surface of the water. To an animal seeking protection against its enemies, by an instantaneous sinking in the sea, this tendency of the shell to float would prove a serious and dangerous impediment, if the animal itself did not possess the means, in some way or other, of increasing on the instant its specific gravity; and it has long been the opinion of naturalists that the siphuncle is subservient to this purpose, although a difference of opinion has prevailed as to the mode of operation. Dr. Hooke, so far back as the beginning of the last century, expressed an opinion that the MVawti/vs had the power of generating air to fill the deserted chambers, and that by the injection or exhaus- tion of this air through the siphuncle, the specific gravity of the shell could be diminished or increased. It is ascertained, however, that there is not any communi- cation between the siphuncle and the empty chambers; and Mr. Parkinson, who, in his ‘Outlines of Oryctology,’ adopts an hypothesis similar to Dr. Hooke’s, suggests that the tube is elastic and dilated by gaseous or aqueous fluids, the alternation of which produces a corresponding change in the specific gravity of the shell. Dr. Buckland are found in different stages of growth, and they always exhibit the usual indications of successive periodic enlargements. Again, Mr. Adams states, “that it does not appear that the female is able to exist long when disengaged from the shell.” How can these facts be reconciled with the theory that the shell is a mere xidus ? * MM. de Blainville and d’Orbigny have founded on these remains two genera, which they have named Conchorhyncus and Rhyncoteuthis. The reasons advanced for supposing that the Rhyncolites were not the mandibles of any of the Nautilidee or Ammonitide already known, are far from conclusive ; and these genera can only be regarded as arbitrary, though perhaps convenient, divisions, according to the peculiar forms presented by the remains. CEPHALOPODA. 9 maintains that a fluid is contained in the pericardium, the position of which is alternately changed from that cavity to the siphuncle ; and that in this shifting fluid the hydraulic balance consists, the chambers being filled with air alone, the elasticity of which would admit of the alternate expansion and contraction of the membranous siphuncle. Prof. Owen has pointed out objections to both these hypotheses. The only organ apparently by which the gaseous fluids of Mr. Parkinson’s theory can be secreted, is a small artery continued down the siphon, but which would not be adequate for the purpose ; and the form and size of the siphon would not allow of an escape of gas so free as to make the consequent sinking of the shell sufficiently rapid for defensive purposes. In some extinct species of Vawti/us the membranous siphuncle appears to have been capable of considerable dilatation, instances of which are mentioned by Dr. Buckland; but Professor Owen states that, in all the specimens he had examined, the membranous siphuncle, after the first chamber, presented an inextensible and almost friable texture, and was coated beyond the extremity of the testaceous siphon with a thin calcareous deposit; and that, in certain extinct species, the testaceous or calcareous siphon extended from septum to septum, rendering a dilatation of the membranous tube physically impossible. The calcareous siphon of the recent Spirula, as is well known, exhibits this form of structure. It is ascertained that, by the conversion of the dwelling-chambers of the animal into what may be termed air-chambers, the specific gravity of the Nautilus, and of its shell, may be maintained nearly in equilibrio with that of the sea. This equilibrium would be very sensibly affected by the position of the body of the animal with reference to the shell ; and Professor Owen therefore inclines to the opinion® that the variation of the specific gravity is caused chiefly by changes in the extent of the surface exposed to the water, according as the body may be expanded beyond the aperture of the shell, or more or less withdrawn within the dwelling-chamber. At the same time it is not improbable that the siphuncle, filled with the fluid propelled into it from the peri- cardium, in consequence of the pressure caused by the contraction of the animal within the shell, may assist in affecting the specific gravity; it certainly, however, does not appear to be capable of varying the specific gravity of the shell sufficiently for the wants of the animal, and that function, if attributable to it, must consequently be merely secondary. I am therefore inclined to agree with M. d’Orbigny, who rejects the supposition that the action of the siphuncle is hydrostatic. That naturalist assigns to the membranous tube which enters the calcareous siphon, and communicates with the pericardial cavity, a function widely different, and only to be called into action when the animal constructs a new air-chamber. ‘ On this occasion,” he says, ‘‘ many difficulties have to be overcome; the extremity of the body is attached above the last * In this opimion M. de Blainville concurs (Mémoire sur Animal de la Spirula, &c.), and he shows that a similar mode is used by the Spirula; the alteration of the specific gravity being effected by the with- drawal of the cephalic mass into a cavity formed by the upper portion of the body. 0) 10 EOCENE MOLLUSCA. septum (en dessus de lu derniére cloison) by two powerful muscles; and the animal, always increasing in bulk, must detach its body, and remove and place itself at a determinate distance whenever it wishes to form a new partition. There must also be left, between the penultimate partition and that which the animal is about to construct, a space to be filled with air, while the animal is always under water.” And M. d’Orbigny therefore suggests “that the membranous tube and pericardial cavity are required, when the new chamber is constructed, to empty the water contained in it, and to fill it with air before the siphon entirely closes its wall in the interior of the new air-chamber.” This hypothesis does not appear to be more satisfactory than the one involving a hydrostatic function. No allusion is made in any way to the attachment of the animal to the shell by means of the horny or epithelial cincture which, as we have seen, encircles the lower part of the body. This cincture, in fact, hermetically closes the space between it and the last septum ; and, unless it is detached, there would not be any external entrance through which the water could penetrate, and the function, the object of the hypothesis, becomes unnecessary. I cannot think therefore that this important attachment was overlooked; and I assume that M. dOrbigny, when he says that the animal “must detach its body,” means that it must detach not only the adherent muscles which he mentions, but also the horny cincture, to which he does not allude. Conceding this to be the case, then, the hypothesis in question assumes that the advance of the body, pre- paratory to the formation of the new partition, is not gradual; but that the animal, by sudden and nearly simultaneous efforts, detaches the adherent muscles and the cincture, and removes its body to the necessary distance. In all other testaceous molluscs, the advance of the adductor and adherent muscles is caused by the depo- sition of new matter, by means of a thin membrane, part of the pallial membrane, interposed between the extremity of the muscle and the inner surface of the shell. The deposition is made, particle by particle, on the anterior part of the muscle, portions of the posterior part probably becoming detached and absorbed; but this process is so gradual, that the attachment of the animal to the shell—an attachment, in fact, necessary to its existence—is not affected; and thus the muscle advances slowly and imperceptibly. There does not appear to be any reason for supposing that a law prevails among the cephalopodous molluscs different from that which regulates the advance of the adherent muscle in the testaceous gasteropod. We may readily conceive, on the contrary, that the entire detachment of the muscles and of the cincture would be attended with considerable inconvenience to the animal; for, in that condition, the fulerum or resisting power by which the animal is enabled to use its tentacles and other organs efficiently, and which is essential to its existence, would be temporarily lost. The sudden removal of the body forward would probably, although it cannot be assumed that it would necessarily, cause the rupture of the membranous siphon, for that organ may be sufficiently elastic to stretch to the required CEPHALOPODA. 11 distance ; but the rupture is, in fact, required by the hypothesis, and the animal would thus be deprived at once of all its means of attachment to the shell. Neither by this periodic advance would the equilibrium of the specific gravity be maintained. We are warranted, I think, in assuming that the specific gravity of the animal and its shell, without the siphuncular aid, would be most nearly in equilibrio with that of the surrounding sea immediately after the formation of a new septum. Now the growth of the animal would constantly tend to derange this equilibrium, until the period should arrive for the formation of the new septum. ‘The capability of the animal, therefore, to rise and sink would be as constantly fluctuating, unless there existed some mode of compensating for the increasing bulk of the body during the interval between the formation of the penultimate septum and that of the last. This compensation, however, would be provided in the case of a gradual advance of the line of attachment; for the vacated part of the dwelling-chamber, filled with exhala- tions from the animal, and increasing in size as the body is advanced, would become an air-chamber as effective as if it were inclosed by a new septum; while, on the other hand, a periodic advance of the muscles and cincture would deprive the animal of this mode of maintaining the equilibrium. I have mentioned the rupture of the membranous tube, which would be the consequence of the sudden advance of the body ; in fact, the hypothesis which attributes to this tube the function of carrying off the water admitted mto the vacated part of the shell by the detachment of the cincture, requires, ev necessitate, that the tube should be ruptured in order that the water should enter it; and in that case the membranous siphon in the deserted chambers would consist of detached fragments extending from septum to septum, and which, having fulfilled their object and become severed from the animal, would no longer retain vitality. This, however, is not the fact. The membranous tube is continued entire through all the septa to the extreme air-chamber,* and is a vascular organized substance, provided with an artery and a vein for its nutrition; and it maintains its vitality during the life of the animal. We are compelled, therefore, to think that the function of the siphuncle must be coextensive with the animal’s existence. On these grounds, the theory suggested by M. d’Orbigny is not more satisfactory than the hydrostatic theory which he rejects. Whatever the function may be, it is evident that the air-chambers themselves would be as efficient a float without the siphon as with it; and the alteration of the specific gravity, as has been stated, may and in all probability is, effected simply by the animal protruding or withdrawing the cephalic mass from or into the dwelling-chamber of the shell, or, as * Professor Owen, speaking of the specimen of Spirula Peronii ( fragilis), brought home by Sir Edward Belcher, says: ‘‘On gently raising the exposed portion of the siphon with a needle, the soft siphon was withdrawn, without sensible resistance, from the tube of the hard siphon; the siphon so withdrawn must have reached nearly to the innermost whorl. It exhibited a slight segmentation, answering to the suc- cessively sheathed parts of the calcareous siphon.”’ 12 EOCENE MOLLUSCA. M. de Blainville has shown to be the case in Spirula, within a cavity formed by the anterior extremity of the mantle. We may reasonably infer, therefore, that to assist in varying the specific gravity is not the principal function of the siphuncle. But, in any view, the preservation of the deserted chambers, as air-chambers, is essential to the motive power of the animal; for it is only by their tendency to float when the cephalic mass is protruded, that the animal is enabled to rise; and this nicely- adjusted counterpoise is maintained, as we have seen, by the addition of new air- chambers, as the animal and the shell increase in size. It is obvious, therefore, that the hydrostatic balance would be destroyed if any one of the deserted chambers were so injured as no longer to act as a float. Now it is known that the shells of the testaceous molluscs are not wholly inorganic substances ; but that a vital communica- tion is maintained between them and the animals, and that where this communication ceases, the deserted whorls of the shell lose their vitality and become brittle ; the calcareous matter falls off in particles, and the shell is much more susceptible of injury. In Bulimus decollatus (Helix decollata, Linn.) and other similar shells, in which the earlier whorls are wholly deserted, the animal on withdrawing its body forms behind its extremity a concave septum. In these cases the apex of the shell, no longer necessary, is easily broken off; in which state the shell is said to be decollated.* In the siphoniferous shells, however, the preservation of the chambers, as air-chambers, is, as we have already seen, essential to the motive power of the animal. It is true that in the Nautilus, the mode of convolution, upon a vertical axis, is admirably adapted to strengthen and protect the first-formed volutions; but in shells not so constructed, and even in those possessing the nautiliform mode of convolution, it would appear to be essential that the vitality should not be lost. How, then, is the necessary communication between the animal and the air-chambers maintained, and the vitality of the deserted shell preserved? It has been shewn that the siphuncle traverses the chambers to the extreme nucleus of the shell, and that it is provided with a small artery and vein; and we also learn from Professor Owen’s Memoir, that in the Nautilus “a delicate pellicle, distinct from the tube, is continued over the outer part of the testaceous tube, and also over the whole inner surface of the chamber.” May we not then reasonably regard the siphuncle with its artery and vein, and the pellicle lining the air-chambers, as the organs destined to maintain the vitality of the shell, and feel ourselves justified in considering this office to be in fact the primary function of the siphuncle ? And when we bear in mind that the internal shells, from * Tam wholly indebted to my friend Mr. Searles Wood for the following theory as to the siphuncular function, and the main arguments in support of it. The well-known conchological attaimments of that gentleman exact respect for every opinion of his on subjects like the present; but independently of this, the theory itself seems to me to be far more probable than any hitherto advanced as to the office of the siphon ; and I therefore gladly avail myself of Mr. Wood’s permission to introduce his views of the subject into my text. CEPHALOPODA. ‘13 their terminal or, as in Spirula, their exposed position, are particularly lable to injury from the shocks caused by the retrogressive movements of the animals, we shall find that the hypothesis will be as applicable to them as to the external shells. In the extended series of observations made by Dr. Carpenter upon the microscopic structure of shells, it is shown by that gentleman that the outer covering or shelly mass of molluscous animals is invariably permeated by an organized membrane, and he says (Report Brit. Assoc., 1844, page 9): “I am much disposed to believe that in every distinct formation of shell substance there is a single layer of membrane, and I am further of opinion that this membrane was at one time a constituent part of the mantle of the mollusc.” He further represents this membrane to have, more or less, a cellular arrangement, the interstices of which are filled with carbonate of lime or inorganic matter; and, at page 10, he says: ‘‘ Coupling the appearances which I| have myself observed, with the observations of Mr. Bowerbank, on the formation of shell, and keeping in view the general doctrines of cell action which I have elsewhere endeavoured to develope, I am inclined to believe that these cells are the real agents in the pro- duction of the shell, it being their office to secrete into their own cavities the carbonate of lime supplied by the fluids of the animal.” He does not appear to have extended his researches so far as to determine whether any or what amount of vitality is possessed by these membranes; but from the continuity and intimate connexion of * this beautiful network, permeating the entire substance of the shell, we may imagine that some slight degree of vital existence pervades the whole membrane, by which it is possible that the inorganic material is preserved from disintegration. In those shells which appear to have been subject to the erosive action of acidulated waters, or other external agency, such as the apices of Cerithia and the umbones of Cyrene, the part most affected is that which is furthest removed from the main body of the animal ; while that part of the shell which is in close proximity with the mantle is not, or at least but little, altered; probably owing to its greater vitality, and to its being the part most essential for the protection of the animal. Not only is the entire formation of shelly matter permeated by an organic membrane, but in some of the shelly coverings of molluscous animals in the order Brachiopoda, there is a very peculiar structure, somewhat analogous with what has been before suggested as the especial use of the siphuncular tube in the Cephalopoda. Dr. Carpenter has pointed out that in most, or perhaps in all, of the nonplicated species of Terebratula, the whole surface of the shell is perforated with innumerable pores, into which are inserted vascular portions of the mantle of the animal, of a tubular form, and filled with fluid, which have no communication with the exterior, but are closed at-the outer surface of the shell, and occupy the entire space of the pores. These cecal appendages may be for the purpose of distributing a greater degree of vitality through the body of the shell; though for what especial purpose this provision is required in one group more than another, it is not easy to explain; perhaps a greater degree of strength is 14 EOCENE MOLLUSCA. required in the zonplicated shell, for the preservation of an animal, whose habitation, for the most part, is at a considerable depth, where the pressure of water is much increased, than in the plicated species, the peculiar construction of which would afford sufficient resistance, without that additional support which the smoother species may receive from this singular structure of the mantle. If, however, a necessity exist for the preservation of the shell in ordinary cases, how much more essential would it be that some compensating power should be possessed by an animal whose existence, in all probability, is dependent upon the buoyant principle of its partitioned shell; and how probable does it appear that this, an ordinary provision, should be employed for its protection. The tubular character of the siphuncle suggests an hydraulic action. To explain this, it is necessary to invest the animal with the power of emptying and filling the tube at discretion ; and this power it may be presumed to derive from the pressure upon the pericardial cavity, caused by the folding and contracting within the shell of the large cephalic mass. Under this pressure the fluid would be injected the whole length of the siphuncle, and, on the removal of the pressure, would return into the pericardium, to be there renovated and vivified with the other fluids, to be again injected when the animal returns within the shell. If the siphuncle had been a solid body, or composed of muscles, fibres, &c., it would have required to be permeated with arteries, blood- vessels, &c., for its sustenance; but by the simple process of the fluid returning into the body of the animal, all the complicated apparatus necessary to sustain a fleshy body is superseded ; circulation and renovation are accomplished, and the fluid is thus maintained in a condition capable of affording the nourishment to the shell which the present hypothesis requires. The theories here suggested are, as all other theories on the same subject must for the present be, merely speculative; for, to quote the observation of Professor Owen,” “much remains to be done before the theory of the chambers and siphuncle can rest on the sound basis of experiment and observation.” These alone will satisfactorily determine the real purposes of the membranous siphuncle; but, for my own part, I believe that the primary, and probably the only, function of that organ is to maintain the vitality of the shell, and that it may be looked upon as an elongated ceecum ; and that it is not, under any circumstances, used by the animal as a hydro- static balance. It is unnecessary here to particularise the various forms of external shells presented by the extinct tetrabranchiate Cephalopods, inasmuch as, of the numerous genera which swarmed in the ancient seas, only the Nautilus survived the secondary period. The dibranchiate Cephalopods, with the exception of the genus Aryonauta (which, with Bellerophon, constitutes Professor Owen’s family of testaceous Octopods), are without * Memoir on the Nautilus Pompilius, p. 47. CEPHALOPODA. 15 external shells; but they are provided with internal horny or calcareous substances, encysted in the back of the mantle, and frequently not in any way attached to the animal, but loose in the cells containing them. In the naked Octopods these internal substances are of the simplest form, and consist of two short, horny, gelatinous styles. Among the Decapods, they become gradually more complicated in structure. In the Loligide, the Loligopside, and the Teuthide, they assume the form of a horny plate, termed the g/adius, which in some genera is thin and feather-shaped, or more or less spatulate, lanceolate, or ensiform; and in others, they are elongated, narrow, and termi- nated posteriorily by a simple cup-shaped appendage. In the Sepzde the shell presents aseries of thin calcareous plates, not siphoniferous, but separated by numerous exceed- ingly minute pillars, and forming a convex mass terminated by a mucro or spine; in the Belemnitide it consists of a chambered cone perforated by a siphuncle, and lodged in a cavity formed in the upper portion of a calcareous rostrum, more or less pointed or obtuse; and in the Spirulide, the sole remaining family, it is a calcareous, horizontally convolute, multilocular, and siphonated shell, with distinct whorls, and imbedded in the animal, but having portions of the last whorl merely covered by the outer layers of the skin. These differences in structure appear to be always accom- panied with distinct zoological forms ; and hence the Paleeontologist is enabled to form a tolerably correct judgment of the analogy between the existing species and those which inhabited the ancient seas, although the testaceous remains are, most frequently, the only means of comparison afforded to him. These internal shells are formed by secretions, from the internal surfaces of the cells, of a horny or calcareous substance, which is deposited in successive layers, and by the continual addition of which they increase in size as the growth of the animal proceeds. Their functions are various, and in accordance with their particular structure. When the internal shell is gelatinous or horny, as in the Octopoda, and in the Loligide, Loligopside, and Teuthide, the function is chiefly to support and strengthen the body, analogous with that of the bones in the vertebrate animals. It appears that the greater or less length of the shell has always relation to the swimming power of the animal. When the internal shell is horny or calcareous, and contains parts filled with air, as is the case in the several other decapodous families, it acts as a float; and in this function, like the external shell of the tetrabranchiate Cephalopods, it represents the swimming bladder of fish; but the volume of air contained within the shell is, apparently, in an inverse ratio with the swimming power of the animal. In addition to these functions, the internal shells, which are provided with a mucro or rostrum at their posterior extremities, as in the Sepide and Belemnitide, are enabled by its means to break the force of the shocks caused by the body striking against any hard substance in its retrograde motion. In the recent Cephalopods this protection is confined to the Sepidz, the most littoral of all the Cephalopods: to the deep-sea swimmers it is denied; it would in fact be 16 EOCENE MOLLUSCA. useless to them. We may assume, therefore, that in the extinct Cephalopods the presence of the mucro or rostrum will indicate a littoral animal. M. d’Orbigny states that he has always observed in the Sepia, the extremity of the mucro projecting beyond the body, and it is not improbable that this part of the shell may be used, as he suggests, for defensive purposes, and that it is protruded at the will of the animal. The Cephalopods, highly organized as they are in comparison with the other molluscs, are among the earliest forms of animal life which geology has brought to light. The Silurian group, the most ancient fossiliferous formations with which we are acquainted, contains the remains of one species of Nautilus, and of many species be- longing to cognate genera. Several species of Goniatites, an anomalous genus be- longing to the Ammonitide, and connecting that family with the Wawtilide, also occur. As we ascend in the Palzeozoic series, we find that various of the primitive genera and species disappear, and are succeeded by other forms, distinct from, although closely allied to, them ; which, in their turn, are also lost. On passing into the Mesozoic series a marked change takes place. Of the eight genera constituting the family Nautilide, which lived during the Paleozoic epoch, Orthoceras* and Nautilus alone survive ; and of the long series of species belonging to the latter genus, whose remains are found in the carboniferous formations, every one disappears ; but an immense array of Ammonites starts into existence, with septa at first comparatively simple, but be- coming more complicated in structure in the succeeding formations. The dibranchiate Cephalopods now first appear.t In the Oolitic group, twenty-five species of Belemnite, and remains of various genera belonging to the families Loligide and Teuthide, have been found. The Belemnites occur in incredible quantities, and sometimes form entire strata. Passing into the Cretaceous group, we still find the Nautilus, though of diminished importance ; the Ammonites are reduced in number to little more than a fourth part of the species found in the Oolitic group, and new modes of convolution appear in their shells, on which the several other genera constituting the family 4mmonitide are founded. The family itself gradually diminishes as we ascend in the Cretaceous group, and wholly disappears with the secondary period. The Belemnites appear to be the sole representatives of the dibranchiate Cephalopods during this epoch, and with it they also perish. On entering into the tertiary formations we find, that of the rich and varied assemblage of tetrabranchiate Cephalopods which characterised the fauna of the secondary period, only the Wawfi/i survived. On the Continent their remains are found in the Eocene formations, and also in the Miocene formations, at Turin and in Touraine ; but in this country they are confined to the older Eocene deposits. Of * Von Hauer (Nene Cephalopoden aus dem rothen Marmor yon Aussee), describes several Ortho- ceratites associated with Goniatites in the schistose beds of St. Cassian; those beds, I believe, are now generally considered to belong to the Muschelkalk. + The remains described by Goldfuss and Bronn as Spirule, appear to belong to Gyroceras, a genus of the Nautilide. CEPHALOPODA. sly the dibranchiate Cephalopods, two species of Argonaut have been found in the newer tertiary formations on the Continent; and two genera belonging to the family Belemnitide occur in the beds of the Paris basin, and in the Eocene formations of England. The remains of one of these last are very closely allied to the recent Sepia, and have been generally referred to that genus. M. Voltz, in his ‘Observations sur les Bélemnites,’ pointed out certain differences which induced him to propose a new genus, named by him “ Belosepia,” for their reception. The French Paleeontologists reject this genus as having been proposed on insufficient grounds ; but, for the reasons stated in a subsequent part, it ought, as it appears to me, to be retained. The other remains found in the Paris basin, connect Belosepia with Belemnite; and the genus Beloptera has heen established by M. Deshayes for their reception. Both these genera occur in the London clay and in the Bracklesham sands ; and they, together with certain remains found in the neighbourhood of London, and described by Mr. James Sowerby in the Mineral Conchology as Leloptera anomala, and for the reception of which I have proposed the new genus Belemnosis, are the only remains of dibran- chiate Cephalopods which as yet have been found in the tertiary formations of England. That these animals fulfilled in the ancient seas the office of repressing animal life cannot be doubted. The living Cephalopods are voracious in the extreme; and, as we find that throughout the transition and secondary groups the number of the zoophagous Trachelipods is small in comparison with that of the phytophagous Mollusca, it is not unreasonable to seek in the Cephalopods for that check upon an excessive merease of submarine life, which the other zoophagous molluscs were too inconsiderable in number to afford.* There is scarcely any class in the animal kingdom of the anatomy and habits of which zoologists have so long remained ignorant, or of which the systematic arrange- ments proposed have been so conflicting as the class Cephalopoda. Composed, as it is, of animals in their external construction and appearance remote from all others, and widely differing among themselves, we need not feel surprised at the confusion which characterises the older systems, based, as they all were, more or less, on artificial characters, derived from the various conditions of the shell, or from modifications of the dermal system; and the confusion was increased by the introduction among the Cephalopods of numerous microscopic chambered shells, to which M. d’Orbigny gave the name Foraminifera, but which the recent investigations of Dujardin show to have been constructed by an inferior class of animals, belonging or allied to the Zoophyta, and which he has named Rhizopoda. It would be foreign to the purpose to enter here into any history or comparison of the different systems of arrangement which have been proposed. In the eleventh volume of Lamarck’s ‘ Histoire Naturelle des animaux sans vertebres,’ edited by MM. Deshayes and Milne Edwards the reader * See Dr. Buckland’s Bridgewater Treatise, vol. i, chap. xv. 18 EOCENE MOLLUSCA. will find a most comprehensive and able review of the progress of this branch of natural history. The principle of classification adopted by Cuvier removed many of the difficulties and inconsistencies which had previously prevailed; but it was still based, to a great extent, on external characters. Attempts at arrangements, founded on higher characters, were made by different authors; but the imperfect knowledge which existed of the anatomy of the animals, prevented the establishment of a system in which due regard could be paid to affinities indicated by internal organization. Of late years, however, considerable additions have been made to our knowledge of the anatomy of these animals; and in 1830, the arrival in this country of a specimen of the pearly Nautilus, caught off the coast of one of the New Hebrides, enabled Professor Owen to examine the internal structure of that animal, an opportunity which had not occurred to naturalists since the time of Rumphius. The anatomy of various other Cephalopods was also investigated by Professor Owen; and the additional information thus obtained, led that gentleman, in 1836, to propose a system of classifi- cation which, although at variance in many respects with all previous arrangements, was at once received as one founded, in its general principles, on well-defined and natural characters; and this system, accordingly, forms the basis of the more recent classifications.* All the Cephalopods the anatomy of which had been examined previously to the arrival of the pearly Nautilus, respired by the agency of two branchie or gills, and possessed three hearts, a systemic heart, and two lateral hearts; they were also endowed with eight arms furnished with suckers, some genera having also two elongated tentacula or additional arms. The pearly Nautilus, however, was found to be possessed of four branchiee, and of only one heart; and, instead of arms, the mouth of the animal was surrounded by numerous short tentacula. Availing himself of these natural and well-defined characters, Professor Owen divided the Cephalopoda into two orders: lst, Dibranchiata, comprising those furnished with two gills; and 2d, Zetra- branchiata, comprising those furnished with four gills. The Dibranchiata were subdivided into two sub-orders or tribes, according to the number and condition of their locomotive organs; the first tribe (Octopoda) consisting of the Cephalopods with eight arms, having the suckers simple, and the branchial chamber divided by a diaphragm; the second tribe (Decapoda) consisting of those Cephalopods possessed * Up to this time Spirula, as well as Belemnites, had been classed with Nautilus, and the other Cephalopods which now form the tetrabranchiate order (Ceph. test. polythalamaces of Lam. ; Siphoniferes of D’Orb.) Of the anatomy of the animal nothing was known; but the presence of an ink-bag, and the acetabuliferous character of the arms had been shown by Lamarck and Peron; and from this fact Professor Owen, aided by that knowledge of the laws of correlation which imparts such value to all his observations, inferred that the animal must present the dibranchiate type of structure. The accuracy of this deduction is now fully established. CEPHALOPODA. 19 of eight arms, and two additional elongated tentacula. In this tribe the suckers are armed, and the mantle supports two lateral or terminal fins. The ‘‘ Octopoda’ were divided into two families, termed “ Wuda” and “ Testacea,” according to the absence or presence of an external shell. In the second family was placed Bellerophon, an extinct genus proposed by De Montfort for remains peculiar to the Paleozoic series, which Defrance had associated with Argonaut, but which subsequently had been considered as belonging to a heteropodous mollusc. The reasons which induced Professor Owen to restore Bellerophon to a‘place among the Cephalopods are not stated. If however, its remains belong to this class, they present the anomaly of the testaceous Octopods having been without a representative from the end of the carboniferous epoch until the deposit of the newer tertiary formations, when the family reappears in the genus Argonaut. The decapodous Cephalopods were divided into four families, according to the position of the fins, the nature of the internal shell, and the condition of the infundibular cartilage. The ordinal and sub-ordinal distinctions of Professor Owen have been adopted by M. Deshayes, but that naturalist has subdivided the Octopoda and Decapoda each into two groups; the Octopoda according to their possessing one or two rows of suckers, and the Decapoda according to the position of the fins. These characters appear to be of secondary importance, and, by themselves, can scarcely be considered as sufficient for more than generic distinctions. M. d’Orbigny has availed himself of the presence of suckers and tentacles, characters originally proposed by himself and M. Ferussac as ordinal distinctions, and accordingly the Cephalopoda are divided by him into Acetabulifera and Tentaculifera. The sub- ordinal distinctions of Professor Owen are adopted by this author ; but in his subdivision of Octopoda he has drawn his characters from the presence or absence of the apparatus for resistance, and the aquiferous pores. The Decapoda are arranged by him in two groups, according to the modification in the structure of their eyes, to which I have before alluded. The first group (J/yopsid@) is divided into three families. In two of these, Sepide and Loligide, the characters are taken from the retractile power of the tentacular arms, the condition of the internal shell, and the presence or absence of an eyelid of a part of the auditory apparatus called by him the auricular crests (erétes auriculaires), and of a superior ligament to the funnel; the character of the third family (Spzrulide) rests entirely on the internal shell. The second group (Ozgopside) also consists of three families, two of which, Loligopside and Teuthide, depend on the presence or absence of a lachrymal sinus and the auricular crests, on the funnel being or not being provided with an internal valve and ligaments, on the condition of the aquiferous pores, and on the shell being with or without air-chambers. The Be/em- nitide, the third family, is separated entirely by the character of the internal shell. The peculiar modifications in the structure of the eyes among the decapodous Cephalopods appear to be of sufficient importance to justify the subdivision of that sub-order into the two groups proposed by M. d’Orbigny ; and inasmuch as the adoption 20 EOCENE MOLLUSCA. of that division involves the distribution of the genera forming Professor Owen’s extensive family Zewthide between the two groups, and the characters on which M. d’Orbigny has formed his families are at the least of equal importance with those used by Professor Owen, I have adopted the classification proposed by M. d’Orbigny, but with the following modification. That author has placed Beloptera and Spirulirostra among the Spzrulide. Now the shells of these genera present a series of siphonated air-chambers associated with a rostrum, and therefore bear a much closer affinity with Belemnite than with the shell of the recent Spirula. I have, therefore, placed them, as well as Belemnosis, among the Belemnitide ; and as I agree with Voltz in considering Belosepia to have possessed a camerated and siphoniferous shell, I have also placed that genus in the same family, notwithstanding the close affinity between its remains and the internal shell of the recent Sepia. CLASSIFICATION OF THE CEPHALOPODS. CEPHALOPODA. MOLLUSCA Octopoda Dibranchiata (Acetabu- lifera; Fer. et d Orb.) D dae E ecapoda Tetrabranchiata. (Siphonifera; Fer. et d’ Orb. Tentaculifera ; d’ Ord.) Octopidee Philonexidee Myopside . . Oigopside . . Nautilidee Clymenide . Ammonitidze ‘Sepide . . Loligidee Spirulide . . Loligopsid . Teuthidee . . Belemnitidee . Eledone. Octopus. *\ Pinnoctopus. Cirroteuthis. Argonauta. ( Philonexis. ‘Cranchia. Sepiola. Rossia. Sepia. : | Sepioloidea, | Spirula. Loligo. Sepioteuthis. Teudopsis. Leptoteuthis. Beloteuthis, {~ . . Loligopsis. Chiroteuthis. Histioteuthis. Onychoteuthis. Enoploteuthis. Kelzeno (Acanthoteuthis, Wagr.) Ommastrephia. Belemnosepia Agaz. (Geoteuthis, Muns.) Belosepia. Beloptera. Belemnosis. Spirulirostra. Conoteuthis. [Betemtella Belemnitella. Belemnites. “Nautilus. Planulites (Lam). Gyroceras. Lituitus. Campulites, Desh, (Cyrtoceras, Goldf.) Phragmoceras. Orthoceras. Actinoceras. Koleoceras (Portl). Poterioceras M‘Coy (Gomphoceras, Sow.) Aturia. eancin Turrilites. Helioceras. Goniatites. Ammonites. Crioceras. Scaphites. Ancyloceras. Hamites. Toxoceras. Ptychoceras. ( Baculites. 22 EOCENE MOLLUSCA. OrpER—DIBRANCHIATA. Sts-orperR—DECAPODA. Tribe—OIGOPSID®. lst Family—BELEMNITID2. The Belemnitide, the sixth family in the classification proposed by M. d’Orbigny, consist, according to that author, of the genera in which the animal was provided with an internal horny or calcareous shell, having at the posterior part air-chambers superimposed in a nearly straight line in the form of a cone, and pierced on the ventral part by a marginal syphon. The family is confined, according to that author, to the three extinct genera, Conoteuthis, Belemnitella, and Belemnites. The two latter genera, however, do not appear to fall strictly within the terms of the definition; for the posterior parts of their shells consist, as is well known, of a spathose guard, frequently of considerable size, the anterior extremity of which is produced so as to form an alveolus for the reception of the phragmocone. If, as the fact is, the genus Belemnites forms the typical genus of the Belemnitide, it would surely be proper that those genera which, like the type, possess camerated siphoni- ferous shells, terminated posteriorily by a calcareous guard, should, at all events, be included in the family. It is difficult therefore to conceive on what sound principle Spirulirostra and Beloptera, but more particularly the last genus, whose calcareous remains present so striking a resemblance to those of Belemnites, instead of being placed in this family, have been associated with Spzrw/a, with whose spiral discoidal shell they present so little analogy. It appears to be desirable that, for the present at least, the Belemnitide should be extended so as to comprise all the genera in which the animal possessed an internal horny or calcareous shell, with or without a terminal guard, but containing air- chambers pierced by a ventral siphuncle ; whether those chambers were superimposed in a nearly straight lme in the form of a cone, or ina spiral or subspiral line. As thus enlarged, the Belemnitidz will consist of the following genera: Belosepia, Beloptera, Belemnosis, Spirulirostra, Conoteuthis, Belemnoteuthis, Belemnitella, and Belemnites. Hereafter it may be desirable to form a division for the reception of genera in which, as in Conoteuthis, the apex of the sheath is simple. All attempts at a linear arrangement are absolutely futile ; but it will be seen that in this, as in every case where several genera are grouped together, the family presents aberrant forms leading to other groups; thus Be/optera, Belemnosis, and Belosepia, leading to Sepide; Belosepia and Spirulirostra to Spirulide; and Conoteuthis to Teuthide. CEPHALOPODA. 23 Genus \st. Brvosepta.* Voltz. 1830. Sepia. Cuvier; Férussac ; @ Orbigny ; Deshayes. BELoOsEPIA. Bronn. Animal unknown; but, from the affinities between its calcareous remains and the internal shell of the recent Sepia, supposed to have more nearly resembled that genus than any other existing Cephalopod, and may be thus described : 3 Body oblong, (?) naked, supporting two lateral fins extending its whole length ; mouth terminal, furnished with two corneous mandibles, and surrounded by ten prehensile acetabuliferous arms, of which two were longer than the others ; mantle free at the anterior margin ; dranchie two. Shell internal, oblong, semiconical, coarsely granulated or sulcated on the exterior, internally smooth, containing a series of transverse laminz, perforated near their ventral margins by large elliptical, sub-siphoniform openings, and terminating in a solid beak or rostrum, inflected towards the dorsal aspect, and expanded at the anterior extremity on the dorsal aspect into an elevated callus, and on the ventral aspect into a semi- circular plate bent outwards over the base of the rostrum; the ventral margins of the laminz converging towards the anterior extremity of the rostrum, and connected by a thin calcareous plate. Testa interna, oblonga, semiconicd, externe granulatd, interne levigatd ; septa trans- versa, foraminibus ventralibus ellipticis subsiphonoidis perforata, continenti, et rostro solido, antice, parte dorsali in callum proeminentem, parte ventrali in laminam supra rostrum reflexam dilatato, posticé sursum inflexo, terminatd ; septorum marginibus ventralibus ad basim rostri convergentibus et tenui lamind connexis. The remains of this extinct Cephalopod have been long known as of frequent occurrence in the Paris bas; they were noticed by Guettardt and were described by him as the fossil teeth of sharks. They were also figured by Burtin,{ and by him were considered to be internal bones of a fish’s head. To Cuvier paleontology is indebted for pointing out their true character. In a short notice published in 1824, in the ‘ Annales des Sciences Naturelles,’ that illustrious naturalist referred the remains in question to a cephalopodous mollusc closely allied to the recent Sepia; and, in fact, they, as well as the remains of another extinct Cephalopod which exhibited an unquestionably camerated and siphoniferous structure, and for the reception of which the genus Beloptera had been established by M. Deshayes, were placed by M. d’Orbigny in that genus. M. de Blainville also in the first instance described them as the remains of a Sepia; but afterwards, when he adopted the genus Beloptera for the Sepia * Etym. Bedos, telum ; Xnzia, sepia. + Mémoires sur différentes parties des Sciences et Arts, 1783, Septitme Mémoire, pl. 2, figs. 29-30. t Oryctyographie de Bruxelles (1784), pl. 2, fig. A. 24. EOCENE MOLLUSCA. Parisiensis, he confounded with it the remains in question. M. Voltz was the first to examine these remains with the attention they deserve. This author instituted a com- parison between the shell of the Beloptera Belemnitoidea, that of the Beloptera Sepioidea (Sepia Parisiensis), and the recent Sepzon, and stated the reasons which induced him to consider the Beloptera Sepioidea as belonging to a distinct genus, equally removed from the Beloptera Belemnitoidea and the recent Sepia, and as forming a natural connexion between Belemnites and Sepia; and he proposed the present genus, Belosepia, for its reception. The principal ground advanced by him to justify this separation was, that the remains of Belosepia indicated a camerated and siphoniferous structure in the contents of the sheath, widely different from that of the Sepion ; and, if this opinion be correct, there cannot be a doubt as to the propriety of the separation. M. Deshayes, however, in his ‘ Description des Coquilles fossiles des Environs de Paris, without questioning in any respect the accuracy of M. Voltz’s description, without referring even to that author’s opinion as to the siphoniferous structure of the shell, but simply relying on the analogy drawn from the general resemblance between the remains of the Sepza Parisiensis and the Sepion, unhesitatingly rejected the genus Belosepia as not possessing characters sufficiently distinct from those of Sepia; although he considered that it would be desirable to form a section in the genus Sepia for the reception of the fossil species. In this opmion M. Deshayes has been followed by MM. Pictet and d’Orbigny. I cannot concur with these authors in the rejection of M. Voltz’s genus. The Belosepion®™ appears to me to present peculiarities of structure, indicating corresponding important zoological differences, which render it impossible to regard the animal to which it belonged as forming part of the existing genus Sepia. The Belosepion, like the internal shell of the Sepia, is a compound shell, and consists of—Ist, a solid calcareous mucro, or rostrum, commonly called the beak, inflected at the posterior extremity towards the dorsal aspect, and at the base ex- panding on the dorsal aspect into an elevated, compressed, and more or less rugose mass, called by M. Deshayes the ca//vs, and on the ventral aspect into a thick semi- circular plate, bent outwards, in a radiated fold, over, but not touching, the upper portion of the rostrum, denticulated on the margin, and continued laterally into the parietes of the sheath. 2d. An inverted semiconical calcareous plate, termed the sheath, externally coarsely granulated, internally smooth, but presenting a series of undulating impressions, con- verging towards the inverted apex, where the sheath terminates in a conical cavity, formed in the anterior portion of the rostrum, and strongly inflected towards the ventral aspect, so that the posterior extremity presses against the origin of the radiated fold. * The term Belosepion is used here to describe the entire internal shell of the Belosepia ; in the same way as the term Sepion (Sepiostaire of De Blainville) is used by English writers to describe the internal shell of the Sepia, or what is usually known as “ Cuttlefish-bone.” CEPHALOPODA. 25 3d. A thin calcareous layer, covering the whole of the inner surface and the terminal cavity of the sheath; and 4th. A series of thin laminz or septa imposed one upon another, at first nearly vertically, but assuming gradually a horizontal direction, owing to the convergence, towards the origin of the radiated fold, of their ventral margms, which are nearly straight, and connected by a calcareous plate, forming the ventral surface of the sheath. The undulating impressions which appear within the sheath are strongly defined on the dorsal aspect, but become faint as they approach the ventral surface. M. Voltz has described these undulations as impressions of the sutures of the alveolus ;* while, on the other hand, M. d’Orbigny considers them to be lines of growth, and not marks of the chambers, which, he says, in fact only occupied one half of the cavity. They are, however, strictly analogous with the similar impressions found in the Sepion, and are formed by the margins of the lamin or septa. Beimg formed in succession as the new lamine are added, it is true that in that way they represent the progressive increase of the shell; but they are not true lines of growth. The extreme fragility of the lamine has not allowed of their preservation; but their remains occur, not unfrequently, towards the posterior extremity of the sheath, consisting of fine elevated lines, which traverse the whole circumference of the cavity, and are, in fact, the dorsal and lateral margins of the laminz adhering to the inner sheath. These lines are continued over the calcareous plate, which connects the ventral margins of the laminz ; and it is evident, therefore, that the laminz extended across the whole of the transverse area of the sheath. The ventral margins are always convergent towards the origin of the radiated fold ; and, consequently, the laminz within the terminal cavity slant in a direction opposite to that of the laminz within the sheath, inasmuch as that the cavity extends wholly below the origin of the fold. Owing to this, the arrangement of the chambers formed by the septa somewhat resembles that of the air-chambers in Spirulirostra, except that in the latter shell the plane of the septa is always at right angles with the axis ; while in the elosepion it is at an angle more or less acute as the septa approach to, or recede from, the point of convergence. In the cavity itself, the dorsal margins of the lamine are distant; but as they approach that part of the sheath which is immediately under the point of convergence, they are placed more closely to each other, and they again become distant as the laminze emerge from the cavity. Owing to the convergence of their ventral margins, the laminze, which as they emerge are nearly vertical, take a direction gradually more and more slanting towards the anterior extremity of the rostrum, until, on the shell attaiming its full growth, they assume a position nearly * The word alveolus is used by this author in its original meaning, and is applied to the chambered cone which Professor Owen has named the phragmocone. The term alveolus has been with greater propriety restricted by the latter gentleman to the cavity in which the phragmocone was lodged. “4 26 HOCENE MOLLUSCA. horizontal. This arrangement of the lamine is well displayed in fig. 14, Tab. I, drawn from a specimen found at Sheppy, for the use of which I am indebted to Mr. Dixon, to whom it belongs. The ventral margins of the laminz extend quite across the connecting plate before mentioned; and on each side, at a short distance from the extremities, they expand into the lateral portions of the laminz, small projecting frag- ments of which are sometimes still found adhering to the sides of the sheath. It is evident from this that the opinion expressed by M. Voltz, that there existed in each of the laminze an opening placed near the ventral margin, is correct. These openings appear to have been of an elliptical form, with their shorter axes in a line from the ventral to the dorsal surface, and were lined with an extremely thin calcareous sheath, which extended throughout the whole series of the laminze, and of which portions are frequently found adhering to the immer edges of the ventral margins and the lateral fragments of the laminee. This sheath corresponds with the siphon of the Belemnites, and is represented in the Sepion by the calcareous layer which, extending over the posterior edges of the lamine, covers the entire surface of the last lamina, and it presents, as M. Voltz states, an intermediate form between the narrow, straight siphon of the Belemnites and the wide, open cavity of the Sepion. Whether the spaces between the laminz were filled with minute columnar partitions, similar to those which characterise the Sepion, or whether they were simple air- chambers, we have not at present any evidence to determine. The probability is, that they were simply air-chambers; for no trace whatever of any substance similar to that termed the spongioid tissue of the Sepion has been found, which, had any such substance existed, might reasonably have been expected; and the true siphonal structure, to which the Belosepion presents so close an approximation, is always associated with simple air-chambers. ‘The Belosepion, as its rostrum indicates, be- longed to a Cephalopod eminently littoral in its habits, and the size, notwithstanding the extraordinary development of the rostrum, leads us to believe that the animal was not only smaller, but a less powerful swimmer, than the recent Sepia. We should expect, therefore, to find in it some provision for buoyancy beyond that with which the recent Sepia is furnished, not only for the purpose of increasing the swimming power of the animal, but also as a compensation for the large and dense rostrum and callus which characterise its remains. But if the interlaminar spaces were filled with any substance resembling the spongioid tissue of the Sepion, the floating apparatus of the Belosepion would be apparently inadequate to the wants of the animal. The form and mode of superposition of the laminz, somewhat resembling the arrangement of the septa in Spirulirostra, present a closer analogy with the phragmocone of the Belemnites than with the plates of the Sepion. These considerations give additional weight to the opinion of M. Voltz, founded on the appearance of what he terms the “alveolar sutures,” that the Belosepion was a camerated and siphoniferous shell. The rostrum of the Belosepion presents a structure analogous with that of the CEPHALOPODA. 27 spathose guard of the Belemnite. It has a tendency to split in two along the centre, in a vertical plane, from the ventral to the dorsal aspect; and it is composed of successive conical layers, each enveloping the preceding layer, and exhibiting a fibrous texture crosswise. The anterior lateral and dorsal portions present straight plates, longitudinally fibrous, resembling the structure of the Beloptera Belemnitoidea, and the external edges hang over each other, and give an imbricated appearance to that part of the rostrum. In order to appreciate the differences which appear to render it desirable that the genus Belosepia should be retained, it may be well to give a short description of the internal shell of the recent Sepia officinalis. This will be found to consist of five distinct parts: Ist, an outer layer of calcareous matter, called the dwchler or sheath, convex, rugose externally, and prolonged at the posterior extremity into a calcareous spine, placed in the medial line, and inflected towards the ventral aspect; 2d, a series of horny layers imposed one over another, extending over the posterior dorsal surface of the buckler, and wholly enveloping and extending beyond the spine; 3d, a thin horny layer spread over the whole of the internal surface, and extending beyond the edges of the buckler, and which, in its turn, is entirely covered by, 4th, a calcareous layer, which contains the spongioid tissue and, 5th, a series of convex horny lamine, impregnated with carbonate of lime, placed horizontally, the posterior edge of each succeeding lamina being a little withdrawn from that of the preceding lamina, so that by this mode of superposition they present a depression or cavity immediately above the origin of the spine, and gradually rise into a convex mass at the middle and upper extremity of the shell. The spaces between the lamine act as air-chambers, but there is not any siphuncle or siphonal opening ; and the surfaces of the lamin are studded with an infinite number of minute columnar and sinuous partitions, placed at right angles to the lamin, and giving them support. It will be seen from this that the Belosepion, although bearing a close general resemblance to the Sepion, still presents several strongly-defined differences. The elevated calcareous mass or callus, which, in the Belosepion, terminates the sheath on the dorsal aspect, attaining frequently a considerable size, is not found in the Sepion ; and the fold, which in the latter is represented by a series of horny layers, distinct from, but wholly enveloping, the spine, is, in the former, a thick calcareous plate, formed by the expansion and retroflection of the anterior extremity of the rostrum, and extending barely beyond the line of the callus. In the Sepion the rostrum is small, in some species little more than rudimentary, and inflected, if at all, towards the ventral aspect. In the Belosepion, on the contrary, it attains a very large size, and, as M. Pictet observes, would indicate a gigantic animal if it were in relation to the animal in the same proportion as the Sepion; and it is invariably inflected towards the dorsal aspect. The internal lamine of the Sepion are horizontal, equidistant, and parallel, and so arranged as to form a hollow at the posterior ventral portion of the sheath, but rising 28 EOCENE MOLLUSCA. into an elevated mass towards the middle ; while in Belosepion, after emerging from the terminal cavity, m which they radiate, as it were, from the origin of the fold, they are at first nearly vertical, with the edges of the ventral margins ranged in a line with the ventral surface of the rostrum, and converging towards the inverted apex of the sheath ; so that, as the sheath enlarges, the dorsal edges of the laminze become more and more distant, and the laminz themselves tend gradually towards a horizontal position ; and in fact, in an adult individual, the last laminz become nearly horizontal. Owing to the different mode of arrangement of the lamin, the Sepion and Belosepion differ materially in their shape and general aspect. In each the dorsal plate or sheath is extended so as to embrace the laminz ; but in the Sepion, the lamine of which are horizontal, and placed in a direction nearly parallel with the sheath, it is necessarily much less convex and more extended than in the Pelosepion, in which the laminze, being vertical, or more or less vertically inclined, present to it merely their dorsal and lateral margins. The buckler of the Seyzon, and its contents, are, therefore, in form an elongated oval, depressed in the direction from the ventral to the dorsal aspect, and but slightly convex on the surfaces; while in the Be/osepion the sheath is considerably shorter, enlarging gradually towards the anterior extremity, and presents a deep semiconical cavity, containing within it the whole area of the lamine, and it is obliquely truncated at the anterior extremity, and flat on the ventral surface, which does not extend to half the length of the shell. The most important difference, however, is, that the laminz of the Belosepion possess large ventral, siphonal, or siphoniform openings, a structure which is not found nor represented in the Sepion. These distinctions indicate corresponding zoological peculiarities ; and the animal, although, perhaps, resembling Sepia more closely than any other recent Cephalopod, must yet have presented such marked differences from it as to render it impossible satis- factorily to refer its remains to that genus, and fully to justify the separation proposed by M. Voltz. Ihave, therefore, retained that author’s genus, Belosepia, notwithstanding the array of authorities against it; and I have the less hesitation in doing this, when I find that Cuvier did not refer the remains in question to Sep7a, but to some Cephalopod closely allied to that genus; and that M. de Blainville, when he adopted the genus Beloptera, did not hesitate to remove them from the genus Sepia, to which he had referred them, although he placed them, under some misapprehension, in the genus Beloptera. With respect to the place of Belosepia in the systematic arrangement, as the shell presents a camerated and siphoniform structure and a terminal guard, and is therefore more nearly related to Belemnite than the recent Sepia, I have removed it from the family Sepide, in which M. d’Orbigny has placed it, to the family Belemnitide. It seems to have prepared the way for the recent Sepia, and leads from that genus, by a natural and easy transition through Beloptera and Belemnosis, into Belemnitella and Belemnite. CEPHALOPODA. 29 The specific characters are taken from the rostrum, the callus, and the fold. These parts, however, are of secondary importance only, and would vary in form considerably, not only with the age, but probably with the sex of the animal. Distinctions founded upon them, therefore, must necessarily be somewhat vague and uncertain ; and, in fact, M. Deshayes, from not attaching sufficient importance to changes resulting from age or other circumstances, has proposed three distinct species, viz. Belosepia longispina, B. longirostris, and B. Blainvillii, on remains which, as well as those of the B. Cuvieri (of Deshayes), M. d’Orbigny considers to be varieties of the same species attributable to age. Four well-defined species are known at present, viz. Ist, B. sepioidea (De Blainy.), consisting of S. longispina, 8. longirostris, and 8. Blaimvilhi (Desh.) ; 2d, B. compressa (De Blainv.); 3d, B. Cuvieri (Desh.), which I consider to be the B. Owenii of Sowerby ; and 4th, B. brevispina (Sowerby). With the exception of the B. compressa, which has not yet been found in England, they all occur in the eocene strata of this country. The first three species are found in the Paris basin, and the B. Cuvieri has also been found in the tertiary deposits of Belgium. No. 1. BELOSEPIA SEPIOIDEA. De Blainv. Tab. I, fig. 1 a—. BELOPTERA SEPIOIDEA; De Blainv. 1825. Mal. add. et correct. p. 621, tab. 11, fig. 7. Serra Cuviert; D’Orb. 1825. Tab. Méth. de la Classe Ceph. p. 67. BELOPTERA SEPIOIDEA ; De Blainv. 1827. Mém. sur les Bélem. p. 110, tab. 1, fig. 2, 2a, 26. — — Sowerby. 1829. Min. Con. vol. vi, p. 183, tab. 591, fig. 1 Betosepria Cuviert; Voltz. 1830. Obs. sur les Bélem. p. 22, tab. 2, fig. 6a—g. Srpra Cuviert; Galeotti. 1837. Mém. sur la Constit. Géogn. de la Proy. de Brabant, p. 140. — tLoneIsptna; Desh. 1837. Foss. des Eny. de Paris, p. 757, tab. 101, fig. 4-6. — LONGTIROSTRIS; 35 5 p- 758, tab. 101, fig. 10-12. — Buarnvitir; Li a a Af fig. 13-15. — Cvuviert; Bronn. 1837. Letheea Geognostica, p. 1127, tab. 42, fig. 19 a—e. BELOPTERA LONGIROSTRUM; Morris. 1843. Cat. of Brit. Foss. p. 178. SEPIA LoNGrRostRis ; Pictet. 1845. Traité élém. de Paléont. vol. ii, p. 315. — LONGISPINA; ss es f % — Burarvini; 3 3s 3 — SEPIOIDEA; D’Orb. 1845-7. Moll. viv. et fos. vol. i, p. 269. Betosgrra Cuviert; J. D. C. Sowerby. 1849. Dixon’s Geol. Hist. of Bracklesham, Selsey, and Bognor, &c., p. 109, tab. 9, fig. lla. —_ LONGIROSTRIS ; 39 35 p. 109, tab. 9, fig. 15. _— LONGISPINA ; 3 $ p- 109, tab. 9, fig. 12. — BLAINVILLII ; 3 3 p. 109, tab. 9, figs. 16, 17. Non Serra Cuvrert; Desh. Foss. des Env. de Paris, p- 758, tab. 101, figs. 7-9. B. rostro elongato, crasso, acuto, recto aut plus minusve arcuato ; lamind ventrali crassa, profunde radiatim sulcatd, in margine posteriori denticulatd ; callo dorsali pro- Sunde et irregulariter rugoso, deorsum producto aut erecto. 30 EOCENE MOLLUSCA. This species presents considerable variations in the form, as well of the callus as of the rostrum; and, in fact, M. Deshayes has separated it into the three species B. longispina, B. longirostris, and B. Blainvillii, chiefly on account of the different conditions of the rostrum. M. d’Orbigny, attributing the variableness of the rostrum to the age of the animal, or to alterations caused by fossilization, to which I would also add changes resulting from attrition, has united these species under the specific name B. sepioidea, originally given by De Blainville. Possessing a long series of specimens, comprising individuals in different stages of growth, and in which the peculiarities of form, taken by M. Deshayes as specific characters, appear to pass gradually into each other, I have no doubt as to the propriety of the union, proposed by M. d’Orbigny, of the three species above mentioned. That author, however, has added to them a fourth species, proposed by M. Deshayes, B. Cuviert ; but which, as it exhibits constant and well-defined differences, I think should be retained. The rostrum of B. sepioidea is elongated, and pointed at its posterior extremity; on the inferior or ventral surface it is sometimes, particularly when young, nearly straight, but more frequently it is bent, at about half the length, in an angle more or less obtuse, towards the dorsal aspect; the dorsal surface presents a sharp cutting edge, slightly arched, and, at its juncture with the callus, exhibits a depression, which is strongly marked in mature specimens. At the base, immediately beneath the callus, it is more or less dilated, and it is angulated at the margins; the ventral surface is more or less convex. The ca//us is narrow, compressed, and deeply rugose ; the posterior margin forms an acute angle with the axis of the rostrum, varying con- siderably in different specimens. In some instances the inclination of the posterior margin is at an angle more or less obtuse with the axis of the rostrum; a condition which, as it appears to me, is attributable to the fracture and attrition of the extremity of the callus, as the specimens in which this form occurs present a smooth worn ap- pearance. The ventral plate, immediately beneath the rostrum, is nearly horizontal, but presents a broad undulation, corresponding with the convexity of the ventral surface of the rostrum; the lateral extremities, as they approach the sheath, gradually diminish in breadth, and assume a nearly vertical position. In consequence of this variation in breadth, the ventral plate, which, at the superior margin, is nearly semi- circular, presents a regular semielliptical form on the posterior margin. It exhibits on the ventral surface a series of sulci, radiating from the apex of the terminal cavity, and varying in depth; and it is deeply and sharply denticulated on the posterior margin. As the shell enlarges, the plate is thickened considerably by successive layers added to the ventral surface. The last layers frequently do not envelope, but are a little withdrawn from the margin of, the preceding layers, leaving the previous denticulations partly uncovered ; and consequently the margin of the ventral plate, in an adult specimen, often presents a double row of denticulations. CEPHALOPODA. 31 The lateral portions of the sheath exhibit deep vascular impressions at the posterior extremity. The B. sepioidea is found plentifully at Bracklesham Bay, on the coast of Sussex ; it is also found at Stubbington (near Gosport) and at Sheppy. In France it occurs, according to M. d’Orbigny, in the lower calcaire grossier at Chaumont (en bas), Vivray, and Saint Germain; in the upper calcaire grossier at Chaumont (en haut), Grignon, Courtagnon, Parnes, Muchi-le-Chatel, &c., and, in the sandy beds above the calcaires erossiers, at Tancrou, Aumont, Acy, &c. The specimen (Pl. 1, fig. 14) exhibits nearly the entire form of the shell; it was found at Sheppy, and enriches the cabinet of Mr. Dixon. The length is four inches, and the breadth across the superior extremity of the sheath, if the cast were perfect, would be rather more than an inch. The remains commonly found seldom consist of more than the rostrum, with, occasionally, portions of the ventral plate, and, more rarely, of the posterior extremity of the sheath. The ordinary size of the rostrum is six tenths of an inch* long, and three tenths wide at the superior extremity. No. 2. BrELosEpiA CuviERI. Deshayes. Tab. I, fig. 3 a—e. Serra Cuvrert; Desh. 1837. Foss. des Env. de Paris, p. 758, tab. 101, fig. 7-9. _ — Vyst. 1843. Deser. des Coq. et des Polyp. des Terr. tert. dela Belg. p- 610, tab. 46, fig. 1. — — Pictet. 1845. Traité élém. de Paléont. vol. ii, p. 315. — SEPIOIDEA (sp.); D’Orb. 1845-7. Moll. viv. et fos. vol. i, p. 269. BeLosEPIA OweEnt; J. D. C. Sowerby. 1849. Dixon’s Geol. Hist. &e. p. 109, tab. 9, fig. 13a. Nec Serta Cuviert; D’Orb. 1825. Tab. Méth. de la Classe Ceph. p. 67. Nec BreLosepia Cuviert; Voltz. 1830. Obs. sur les Bélemn. p. 22, tab. 2, fig. 6a-g. Nec Szpta Cuviert; Sow. Min. Con. vol. vi, p. 183, tab. 591, fig. 1. Nec Betosrpra Cuvier; J. D. C. Sow. 1849. Dixon’s Geol. Hist. &e. p. 109, tab. 9, fig. 11a. B. Testa extremitate posticali lateraliter dilatatd ; rostro brevi, crasso, arcuato, acuto, ad basim latissimo ; lamind ventrali arcuatd, profundé sulcatd, in margine denticulata ; callo dorsali profundé rugoso, margine inferiori recto aut sursum vergenti. M. Deshayes, in his description of this species, refers to Beloptera sepioidea (Beloptere de Cuvier) of De Blainville, and to the specimen figured by Mr. Sowerby in ‘Mineral Conchology,’ as identical with it. The description given by M. de Blainville is rather sub-generic than specific, and is too general for the purpose of identity ; but the figures given by him are evidently those of a mutilated specimen of * In stating the size of the shells I have used tenth parts of an inch, in order to facilitate a comparison with the measurements of French shells; as tenths of an inch may be readily, and with sufficient accuracy, converted into “millimetres” by taking 1 tenth as equal to 23 millim. The exact proportion is 305 millim. = 12 inches; i. e. ‘] in. = 2°54166 &c. millim. 32 EOCENE MOLLUSCA. B. sepioidea, and do not correspond with the specific description given by M. Deshayes. Through the kindness of Mr. Sowerby I have had an opportunity of examining the specimen from which his figure was taken, and it is unquestionably a B. sepioidea ; the peculiar form of the rostrum being caused by the fracture of the posterior extremity, and the abrasion of the lower part of the outer layers. The present species is well defined by M. Deshayes; and as I have a series of specimens in different stages of growth in which the distinctions are preserved, I do not hesitate to retain it. The rostrum is short, thick, slightly arched, and very broad at the superior extremity ; on the dorsal surface, at the posterior extremity, it is compressed, and presents a cutting edge for about one half of the length; the superior extremity is marked by a broad depression extending to the callus. The ventral plate is less elliptical, and the denticulations less prominent, than in B. sepioidea. The callus is nearly perpen- dicular to the axis of the rostrum, and enlarges rapidly, owing to the greater width of the terminal cavity. The specimen figured in Mr. Dixon’s work, under the name B. Owenii, appears to belong to this species. Mr. Sowerby was probably induced, by the synonyms quoted by M. Deshayes, to consider the Sepia Cuoiert of that author as identical with the Beloptere de Cuvier of De Blainville; and as the specimen before him could not be referred to that species, he proposed the species B. Owenzi for its reception. The specific name Cuviert, however, having been improperly used by MM. d’Orbigny and Voltz for the B. sepioidea of De Blainville, must now be retained for the present species, to which it was applied by M. Deshayes, and it will consequently supersede the name Owenit proposed by Mr. Sowerby. M. Nyst cites for his specimens M. Deshayes’s description of B. Cuvieri, and has, in fact, copied the figures given by that author. I have therefore considered them as identical. Hitherto, I believe, B. Cuvieri has been found, in England, only at Bracklesham Bay, where it is not by any means common. The French localities quoted by M. Deshayes are Grignon, Courtagnon, Parnes (upper cal. gross.). M. Nyst gives the sandy beds at Boitsfort, Assche, Jette, Foret, Uccle, and Ghent, as the Belgian localities. The length of the rostrum is 3 inch, and its breadth at the superior extremity ‘3 inch. No. 3. BELOSEPIA BREVISPINA. Sowerby. Tab. 1, fig. 2 a—e. BELOSEPIA BREVISPINA; J. D. C. Sowerby. 1849. Dixon’s Geol. Hist., &c., p. 109, tab. 9, fig. 14. B. rostro per-brevi, crasso, acuto, in aspectum ventralem valde convexo et regulariter arcuato ; lamind ventrali profundé sulcatd, vie denticulatad; callo dorsali in margine inferiori compresso, sursum vergenti. CEPHALOPODA. 33 A species much resembling the young of B. Cuvieri; but, according to the few ‘specimens we possess at present, it is distinguishable by the shortness and the greater convexity of the inferior surface of the rostrum, and also by the dorsal surface, which is rounder than in B. Cuviert, slants downwards, and, even in the largest specimens, barely presents the cutting edge which distinguishes the two preceding species. The callus is longer in proportion, and is so much compressed, as to present a narrow, almost a sharp edge; and it enlarges more rapidly than even in the last species, owing to the greater width of the terminal cavity. The ventral plate is semicircular, and nearly smooth on the inferior margin, and, owing to the width of the cavity, is transversely elliptical on the superior margin ; it is also narrower and more deeply sulcated than in B. Cuvieri. The B. brevispina is found at Bracklesham Bay, and is very rare. I possess four specimens of different sizes, which all present the same characteristic form ; but it is not improbable that a larger series would show that the species is but the young form, or at all events only a variety, of B. Cuvieri. The length of the rostrum is ‘2 inch; the width rather less than *2 inch. Genus 2d. BrLopTERA. Deshayes.* Animal unknown, but supposed to have been closely allied to the Belemnite, which, as described by Professor Owen, appears to have been oblong; the head, surrounded by ten arms, (?)} furnished, like those of the recent genus Oxychoteuthis, with a double alternate series of slender, elongated, horny hooks; mandibles horny; (?) the body purse-shaped, conical, elongated, supporting near the middle two lateral fins, rounded and entire along their free margin; inclosing an ink-bag. Shell internal, composed of two cones placed apex to apex, united, and expanding on each side into wing-shaped appendages, obliquely inclined towards the ventral aspect; the anterior cone smooth, longitudinally fibrous, hollowed into a deep conical cavity, containing regular transverse concave septa, pierced by a ventral siphon. B. Testa internd, duobus conis, apice ad apicem conjunctis, formatd ; utroque latere duobus appendicibus aliformis, deorsum inclinatis, sustentd ; superficie dorsali convexd, ventrali concavd ; cono anteriort levigato, longitudinaliter fibroso, cavitati conicd, profunda, septa transversa continenti, excavato; septis concavis, regularibus, siphone ventrali perforatis. Guettard, the first author by whom these remains appear to have been noticed, * Etym. Bedos, telum; zrepoy, ala. + The eight sessi/e or normal arms only have as yet been found preserved. Professor Owen states that the traces of the superadded pair of tentacula are somewhat doubtful. 34 EOCENE MOLLUSCA. described them as the teeth of fish. Long subsequently, M. Deshayes examined similar remains found in the Paris basin; and, having observed in them characters which induced him to refer them to an extinct Cephalopod nearly allied to the Belemnites, he proposed the present genus for their reception. M. de Blainville, whose ‘ Manuel de la Malacologie’ was then in course of publication, and to whom M. Deshayes had communicated his proposed genus, confounded with the remains in question those of the so-called fossil Sepize (Belosepize); but in adopting the genus Beloptera, he divided it into two sections, the first containing the fossil Sepiz, which he characterised as species having wing-shaped appendages united at the superior extremity of the rostrum; the second section containing the true Belopteree, he described as species having the appendages distinct and the cavity conical, and with chambers and a siphuncle. The mistake is continued by M. de Blainville, in the Supplement to his ‘Mémoire sur les Belemnites,’ published in 1827. In 1830, Voltz pointed out the differences which rendered it necessary to keep the two genera distinct ; and, about the same time, M. Deshayes published, in the ‘ Encyclopédie Meéthodique,’ under the article Beloptere, the grounds which induced him to establish that genus. Notwithstanding this publication, however, the error into which M. de Blainville had fallen was repeated by MM. dOrbigny and de Feérussac, in their ‘Histoire des Céphalopodes,’ and by Cuvier, in his Memoir on the bones of the fossil Cuttle-fish, published in the ‘ Annales des Sciences Naturelles.’ Mr. Sowerby afterwards, when he adopted the genus provisionally for the curious and unique fossil obtained from. Highgate, which he published in the ‘Mineral Conchology’ under the name Beloptera anomala, confined the genus to those species which contained a chambered cone like the Belemnites, and referred the species con- tained in M. de Blainville’s first section to the genus Sepia. The absence, in the Highgate fossil, of the lateral wing-shaped expansions, and of the blunt terminal rostrum which characterise the two known species of e/optera, as well as other characters to which I shall hereafter refer, seems to me to require the establishment of a distinct genus for the reception of those remains; and the genus Beloptera will be then confined to those species which possess lateral expansions, and which, as M. Deshayes himself describes them, exhibit an entire conical and chambered cavity, resembling that of the Belemnite, jomed to a terminal rostrum, like that of the Belosepia. As thus restricted, the Beloptere present, at the anterior extremity, a semiconical cavity, slightly depressed on the ventral aspect, in which was contained a thin calcareous layer, covering the entire inner surface. The mner cone formed by this layer contained a series of transverse, regular, and exceedingly thin septa, traces of which, consisting of their sutures or lines of junction with the inner sheath, are very distinct. These sutures, as they approach the ventral aspect, are slightly bent down- wards towards the inverted apex of the cone, and present an acute sinus-like inflection CEPHALOPODA. 35 as they rise over a slight linear elevation, which traverses the whole length of the alveolus, along the medial line of the ventral inner surface, evidencing the presence and position of the siphuncle. The opening, or anterior extremity of the conical cavity, is slightly elliptical, having the shorter axis in the direction from the ventral to the dorsal aspect. The margin of the outer sheath is thin and sharp, and its ventral paries is much thicker than the dorsal paries, and rises into an elevated mass, depressed on the surface. The outer sheath itself is composed of a series of concentric layers, and exhibits a fibrous texture, like the sheath of the Belemnite. The apex is pro- longed into a dense calcareous mass, strongly inflected towards the ventral aspect, and enlarged towards the posterior extremity, where it becomes attenuated, and is obliquely truncated. This mass is composed of longitudinal laminz, radiating from the apex of the cone, and so arranged, that the central lamine are ina plane extending from the ventral surface to the back, and the rest in planes gradually diverging more and more towards the back. The outer edges of the lamine are distinct and slightly elevated, giving a rough sulcated appearance to the surface. The cone and the calcareous mass into which it is prolonged expand laterally into two smooth semi- elliptical appendages, inclined obliquely towards the ventral aspect, thin and sharp on the outer edges, and gradually thickening as they approach their bases. These expansions consist of two distinct series of layers, deposited on the ventral and dorsal surfaces, and exhibit impressions which, as M. Deshayes remarks, are probably attributable to the presence of a vascular system in the substance of the mantle. It will be seen from the foregoing description that e/optera presents a much closer analogy with the Belemnites than that exhibited by Belosepia. The open semiconical cavity of the latter, in its typical form, nearly resembles the sheath of the Sepion ; but the lamine, both in their mode of arrangement and in their large siphoniform openings, present the first indications towards the phragmocone of the Belemnite. In the aberrant form, Pelosepia compressa, both the sheath and the laminz recede a step further from the Sepion type, and prepare the way for, and in fact connect Belosepia with, Beloptera. In this genus a still nearer approach to Belemnite appears; the wide, open, but shallow sheath of the Sepion, with its siphonless and nearly parallel laminz, is lost, and is replaced by an entire conical sheath, con- taining regular transverse septa perforated by a siphuncle, and exactly corresponding with the sheath and phragmocone of the Belemnite. The fold of the Belosepion, formed by the retroflexion and lateral enlargement of the ventral paries of the sheath, largely developed in the typical form, disappears in Peloptera, and is represented by the lateral expansions which characterise that genus, and which, greatly reduced in size in Beloptera Levesquei, lead directly into the simple sheath of the Belemnite ; while the strongly inflected rostrum of the Belosepion assumes the form of a somewhat conical mass, and thus prepares the way for the elongated and regularly conical guard of Belemnite. 36 EOCENE MOLLUSCA. Exclusive of the Beloptera anomala (Sow.), for which I have proposed the genus Belemnosis, only two species of Beloptera are as yet known, 1. e. B. Belemnitoidea, and 4b. Levesquei. Both species occur in the Paris basin, and in the Eocene beds of England. The first has also been found at Laeken in Belgium, and at Biaritz. The specific characters are taken from the conditions of the lateral expansions and of the conical sheath. No. 4. BELOpTERA BELEMNITOIDEA. De Blainville. Tab. 2, fig. la—g. Toorn oF A FISH; (2) Guettard. 1783. Mém. sur les Glossopétres, tab. 2, figs. 10, 11, 12. Betoptera BELEMNITOIDEA; De Blainv. 1825. Mal. add. et correct. p. 621, tab. 11, fig. 8. Serra Parisrensis; Fér. et D’Orb. 1825. Tab. Méthod. des Céph., Ann. des Sc. Nat. vol. vii. BELOPTERA BELEMNITOIDEA ; De Blainv. 1827. Mém. sur les Bélemn. p. 111, tab. 1, figs. 3, 3a, 30. — - J. D. C. Sowerby. 1829. Min. Con. vol. vi, p. 183, tab. 591, fig. 3. BELOPTERA BELEMNOIDEA; Voltz. 1830. Obs. sur les Bélemn. p. 20. BeLoprera BELEMNITOIDEA ; Deshayes. 1830. Encye. Method. vol. ii, p. 135. a= — Keferstein. 1834. Die Naturgeschichte der ErdkGrpers, &e. p- 430, No. 2. - _— Deshayes. 1837, Descrip. des Foss. des Eny. de Paris, p. 761, tab. 100, figs. 4-6. — — Bronn. 1837. Lethea Geog. p. 1129, tab. 42, fig. 18a-6. — — Fér. et D’ Orb. 1839. Céph. Acetab. Seiches, tab. 3, figs. 7-9 ; tab. 24, figs. 11-12. - - Nyst. 1843. Deser. des Coq. et des Polyp. foss. &c. p. 612, tab. 6, fig. 2. = Pictet. 1845. Traite élément. de Paléont. vol. ii, p. 316; tab. 14, fig. 2. — _ Deshayes. 1845-6. 2d Edit. de Histoire Nat. &e. p. 243. = — D’ Orb. 1845-7. Moll. viv. et foss. vol. i, p. 308, tab. 14, figs. 1-4. — — J. D.C. Sowerby. 1849. Dixon’s Geol. Hist. of Bracklesham, &e. p. 109, tab. 9, fig. 18. B. testd ovato-elongatd, longitudinaliter recurvd; supra converd ; subtus concava, depressa ; cavitate anticd sub-cylindricd : rostro obtuso, striato: appendicibus lateralibus magnis, semicircularibus. Shell oblong, compressed; the sheath straight and nearly elliptical; the ventral paries considerably thickened and depressed on the medial line below the siphuncle, so as to present an elevated sub-quadrate ridge, bifurcated at the posterior extremity. The rostrum enlarges gradually for about two thirds of the length, and then diminishes towards the extremity, which, in young specimens, is nearly conical in form, but in adult ones becomes very obtuse, probably from attrition; it is inflected towards the ventral aspect whence the shell presents longitudinally a somewhat arched appearance. The CEPHALOPODA. 37 lateral expansions are inclined towards the ventral aspect, and give a convex form to the dorsal surface, and a corresponding concavity to the ventral surface; they are thick at the juncture of the rostrum and sheath, and become gradually thinner as they enlarge, presenting a sharp cutting edge on their free outward margins. In this, the typical species, they are largely developed, regular in form, and vary considerably in size according to the age of the individual; in young specimens they present an elongated semielliptical form, which, as the shell advances towards maturity, becomes nearly semicircular. Figs. 1f and lg represent a variety in which the inferior cone is shorter, broader, and more compressed, and the wings are wider than in the ordinary specimens. The B. Belemnitoidea is found in England at Bracklesham Bay, where it is some- what rare. In France it is found in the nummulitic bed at Biaritz, in the Lower Pyrenees ; the lower beds of the calcaire grossier at Vivrais, Grypseuil, and Pouchon (Oise), and, in the middle beds, at Grignon, Parnes, Muchi-le-Chatel, Chaumont, &c. It also occurs in Belgium, in the sandy beds at Laeken. The size is eleven lines in length, and four lines and a half in width across the widest part of the lateral expansions. No. 5. BrLopTera LeEvEsQuE!. D'Orbigny. Tab. 2, fig. 2a—e. Bexoprera Levesauet; D’ Orb. et Fér. 1839. Céphal. Acetab. Seiches, tab. 20, figs. 10-12. — - Pictet. 1845. Traité élément. de Paleont. vol. ii, p. 316. B. testa oblongo-elongatd, arcuatd, subtus carinatd, lateribus depressd, sub-excavatd ; antice cylindrico-angustatd : rostro obtuso, striato: appendicibus lateralibus parvis, linearibus. Shell elongated, arched: the sheath straight and nearly cylindrical; the ventral paries thickened, and laterally much compressed, so that, instead of the flat square- shaped, bifurcating ridge which distinguishes the preceding species, it presents along the middle of the sheath, beneath the siphuncular line, a somewhat acute angular keel, which is continued on the upper part of the rostrum, and the sides of which are a little depressed. The rostrum itself is larger, and is transversely more compressed, and less inflected towards the ventral aspect, than that of B. Belemnitoidea. M. d'Orbigny describes the species as destitute of lateral expansions ; but, in the figures given by him, there are unquestionable indications of those appendages, very slightly developed it is true, yet still representing the wing-shaped expansions which characterise the genus. In one of the two English specimens, the only two with which I am acquainted, and for the use of which I am indebted to Mr. Wetherell, the lateral expansions are broken away, but their existence is evidenced by a deep suture on each side where they were inserted into the shell. The other specimen unfortunately is broken off just above the juncture of the sheath with the rostrum, at the precise part 38 EOCENE MOLLUSCA. at which the expansions would first appear ; but their presence is indicated by a slight curve in the outline caused by their origin. I do not hesitate, therefore, to attribute to this species the characteristic lateral enlargements, although they are very feebly developed. M. Deshayes, in his ‘ Description des Coquilles fossiles des Environs de Paris,’ mentions a specimen in his possession, too much mutilated for description, in which the rostrum is smoother and more elongated, and the wings appear to be much narrower than in B. Belemnitoidea, and not to be inclined downwards as in that species ; and for which, when better known, he thinks it will be necessary to form a new species. May not that specimen be referred to this species, which has been established since the publication of M. Deshayes’s work ? The English specimens of this species have hitherto been found only at Highgate, and are exceedingly rare. In France, according to M. d’Orbigny, the species occurs only in the lower strata of the Paris basm; that is to say, in the sands below the nummulite bed, at Thury-sous-Clermont, Gilocourt, and Cuise-Lamotte (Oise). The size is twelve lines long and three lines wide. Genus 3d. BELeMNosts.* F. £. Edwards. Betorrera; J. D. C. Sowerby. Animal unknown but supposed to be closely allied to the Belemnite. Shell internal, oblong, semiconical, with the apex inflected towards the ventral aspect, and enlarged into an obtuse umbo, pierced by a pore on the ventral surface ; the anterior part hollowed into a deep semiconical cavity extending to the pore, and having the inner surface covered by two calcareous sheaths, one within the other, continued over the ventral surfaces of, and enveloping, a series of transverse septa, perforated by a ventral siphon. Testa internd, oblongd, semiconicd, apice deorsum inflecto et in umbonem obtusum, Jforamine perforatum, dilatato ; parte anteriori in cavitatem semiconicam, profundam, ad foramen tendentem, et septa transversa, siphone ventrali perforata, continentem, eacavata ; cavitatis superficie duobus laminis conicis, pertenuibus, circa septa productis et ea invol- ventibus, obtectd. The remarkable remains for the reception of which I propose the present genus are described by Mr. J. Sowerby in the ‘Mineral Conchology,’ and are referred by that author to Beloptera. M. Deshayes, in the first instance, in the ‘ Description des Coquilles fossiles, &c.,’ expressed an opinion that they could not be placed in that genus; subsequently, however, in the notice of the genus Beloptera, introduced in the second edition of Lamarck, after speaking of Belop. Levesquez, he refers not only that * Etym. Bedepuvoy, telum; evwas, conjunctio. CEPHALOPODA. 39 species but also the Beloptera anomala of Sowerby to the genus Beloptera, the principal character of which he states to be the association of a conical chambered cavity, similar to that of the Belemnites, with the beak (rostrum) of the Sepia. M. d’Orbigny also (Moll. viv. et foss.) refers to that genus the remains in question, which, he says, resemble Beloptera Levesquei in the absence of the lateral wings, but are distinguished from it as well by the want of the under part (the ventral paries) of the shell and of a distinct beak,.as by the air-chambers being apparent on the under side. These remains unquestionably bear a close affinity to Beloptera; but the peculiarities they present appear to me to separate them distinctly from that genus, and fully to justify the establishment of a new genus for their reception. The shell of Belemnosis consists of an elongated semiconical sheath, the apex of which expands into a short semicylindrical umbo, pierced on the ventral surface, and inflected towards the ventral aspect. The sheath is convex on the dorsal surface, and is without a ventral paries; the margins at the superior extremity are narrow, and present outwardly sharp edges, which extend rather more than one third of the length of the shell; as the margins approach the inferior extremity they expand, and the inner edges gradually become nearer to each other, until they unite immediately above the umbonal pore. The margins of the pore are elevated, and the pore itself penetrates to, and communicates with, the air-chambers. The septa are transverse and concave ; the presence of a siphuncle and its ventral position are indicated by angular inflections on the sutural impressions along the medial line of the ventral surface; the septa are contained in, and wholly enveloped by, a thin conical sheath, which also is covered by a second and somewhat thicker conical layer lodged in the outer sheath. The principal character of Be/optera, viz., the association of the elongated rostrum of the Sepion with the phragmocone of the Belemnite, fails in Belemnosis ; and the lateral expansions which, assuming their fullest development in Beloptera Belemnitoidea, still characterise B. Levesquei, although reduced in that species to prominent carinze, are here wanting, or, at the utmost, are but feebly represented by the sharp outer edges of the ventral margins of the sheath. In Be/optera, the outer cone, which contains the inner sheath and its contents, and which exactly corresponds with the phragmocone of the Belemnite, is entire; whereas, in elemnosis, the ventral paries is wanting, or very thin. In this respect Belemnosis presents an analogy with Belem- nitella (D’Orb.), a genus of the Belemnitidee, characterised by a fissure in the phrag- mocone communicating with the external paries of the alveolus. This peculiar form of Belemnite at present appears to be confined to the upper chalk formation, and it would seem to connect the true Belemnite with the present genus, in which the fissure be- comes largely expanded, resembling the wide cavity of Belosepia. Thus the transition from Belosepia, through Belemnosis and Belemnitella, into Belemnite will be easy and natural, and the chain of connexion between the latter genus and the recent Sepia will be complete. 40 EOCENE MOLLUSCA. The principal character, however, which distinguishes Belemnosis is the aperture forming a communication between the alveolar chambers and the sac in which the shell was lodged. In all the camerated siphoniferous shells, I believe without exception, the inferior extremity of the alveolus and phragmocone is perfectly closed, and the air- chambers have not any direct communication with the pallial sac; and, in fact, commu- nicate only with the pericardial cavity by means of the membranous siphuncle. Walch, it is true, in his ‘ Recueil de Monumens, &c.,’ figured a Belemnite, which he described as having a small circular hole at the extremity of a curved point; upon which figure, with embellishments of his own, De Montfort proposed the genus Paclites, referred to by Parkinson, and quoted by De Blainville. This genus, however, is universally rejected, as founded on characters merely accidental or imaginary. M. dOrbigny states, that in certain exceptional cases the extremities of the rostra of Belemnites, at the last period of their growth, form tubular prolongations, and that they are also lable to distortion from accident. The extreme points of the successive layers, which form the spathose guard, are apparently, in some instances, more susceptible of disintegration than the other parts, and thus tubular openings may be formed along what Voltz terms the apicial line. But in all these cases the pore is merely terminal, and does not extend far up the sheath. The structure found in el/emnosis, therefore, appears to be peculiar to it; and would indicate an application of the siphuncular function, whatever that function may be, different from that in all other siphoniferous shells, and suggests a corresponding peculiarity in the organization of the animal. From the absence of the elongated rostrum which characterises the Belosepia and Beloptere, we infer that the animal of Le/emnosis was not littoral in its habits, but existed in a comparatively deep sea; and the occurrence of the unique specimen, upon which the genus is founded, at Highgate, where the organic remains indicate a shallow-sea deposit, is attributable most probably to the casual drifting of the animal. No. 6. BrLemnosis pricata. ff. L. Hdwards. Tab. 2, fig. 3a—e. BELOPTERA ANOMALA; Sowerby. 1829. Min. Con. vol. vi, p. 183, tab. 591, fig. 2. — Morris. 1843. Cat. of Brit. Foss. p. 178. — — Pictet. 1845, Traité élement. de Paleont. tom. ii, p. 316. — — Deshayes. 1845-6. 2d Edit. de Hist. Naturelle, &c. par Lam. = — D Orbigny. 1845-7. Moll. viv. et foss. tom. i, p. 309, tab. 14, figs. 8-10. B. testdé oblongo-elongatd, supra convead, umbone obtusissimo, lateraliter compresso, et deorsum leviter inflecto terminatd: marginibus ventralibus antice depressis, postice sub-convevis, facies externas acutas, internas, oblique triplicatas, prebentibus: foramine umbonali circulari. CEPHALOPODA. Al This shell is oblong, regularly convex on the upper surface, and terminated by a very obtuse, short umbo, compressed laterally, and slightly inflected towards the ventral aspect. The ventral margins are depressed, and present outwardly sharp edges, which extend rather more than one third of the length of the shell; the margins assume a convex form as they approach the inferior extremity, and at about two thirds of the length, become and continue nearly parallel until their union above the um- bonal pore. The inner edges present three obscure, very oblique folds, from which character the specific name is taken. The umbonal pore is circular, and extends to the pyrites, with which the phragmocone is filled ; it is about one fourth of the breadth of the shell in diameter. The septa are distant. This unique and valuable specimen enriches the cabinet of Mr. Sowerby, whose kindness in conceding the use of it for description I beg to acknowledge. It was found in the clay removed in constructing the archway at Highway. The length is °5 in.; the breadth at the upper extremity is *25 in., and across the umbonal pore *15 in. Orper—TETRABRANCHIATA. Owen. Family—NavtTiLiv&. According to Von Buch, the division, which has been made of the tetrabranchiate Cephalopods into the two great families Nautilide and Ammonitide, has been determined solely by the position of the siphuncle, which, in the latter family, is invariably placed on the ventral margins of the septa; while, among the Wautilide, it is placed at or near the centre of the discs of the septa. Other differences exist in the form and condition of the septa, which, among the Wawtilide, are characterised by simple curvatures or undulations, and by having their margins entire; while, among the dmmonitide, the septa present a series of lobes or sinuous flexures, the margins of which are foliated. A third group, however, exists, m which the siphuncle is placed on the dorsal margin, and the septa are distinguished by angular or rounded lateral lobes, but their margins are perfectly simple. This group, for the typical forms of which Count Mister established the genus C/ymenia, has been hitherto generally associated with the Nautilidz ; but I propose to separate it as a distinct family, under the name Clymenide. The Nautilide will then be confined to those genera in which the siphuncle is central or excentric, that is, placed at the centre of the disc of the septum, or between that and the margin; or, more strictly, to those in which it is not placed either on the ventral or on the dorsal margin. As thus restricted, the Nautilide will consist of the following genera: Nautilus, 6 42 EOCENE MOLLUSCA. Planulites, Lam., Gyroceras, Lituitus, Campulites, Desh. (Cyrtoceras, Gold.), Phragmo- ceras, Orthoceras, Actinoceras, Koleoceras, Portl., and Poterioceras, M‘Coy (Gom- phoceras, Sow.) Of these genera, the Nautilus only has been found above the secondary formations. The generic distinctions are taken chiefly from the position of the siphuncle, and the mode of convolution or the form of the shell. Genus 4. Nautitus—Gualtieri, Linneus. Ocranus; BrsipHites. De Mont. OmpuaLia. De Haan. Gen. desc. Animal; 4ody oblong, posteriorly rounded, and terminating in a slender membranaceous tube ; head above, with an ambulatory disc ; arms, nineteen (?) on each side ;* /abial tentaculiferous appendages, four, arranged round the mouth; tentacula of three kinds, viz. ophthalmic, lamellose, two on each side ; brachial, annulose, twenty on each side; /adia/, annulose, twenty-four on each side; the whole body contained in the last chamber of a large multilocular shell, and affixed by two lateral muscles. Shell; discoidal, spiral, multilocular, with simple walls; the whorls contiguous, the last covering the others; septa transverse, concave without, perforated in the disc, margins quite simple. Animal corpore oblongo, postice rotundato, tubo gracili membranaceo terminato ; capite supra disco ambulatorio ; brachiis utrinque novemdecem ; (?) appendicibus labialibus ten- taculiferis, guatuor, circum os dispositis ; tentaculis trium generum, quorum, ophthalmicis, lamellosis, utrinque duobus ; brachialibus, annulosis, utrinque viginti ; labialibus, annulosis utringue viginti quatuor ; toto corpore in camerd ultima teste magne multilocularis recon- dito et musculis duobus lateralibus affixo. Testa discoided, spirali, polythalamid, parietibus simplicibus ; anfractibus contiguis, ultimo alios obtegente ; septis transversis, extis concavis, disco perforatis, marginibus siemplicibus. The Nautilus is the only genus of the Cephalopoda which, appearing among the earliest forms of animal life, has survived the various changes which the earth has undergone. The large family, of which it forms the type, flourished during the Paleozoic epoch, and the Nautilus itself apparently attained its fullest development during the deposition of the carboniferous series, at which period nearly fifty species existed. Gradually diminishing in numbers, the genus passed through the Mesozoic epoch into the tertiary era, which it has also survived; and though reduced to four species, which have not any fossil representative,t it still exists in the tropical seas. * M. Valenciennes states the number to be seventeen. t The identification of the species in the Miocene formations of Turin cannot be relied upon. CEPHALOPODA. 43 The Nautilus appears to have been known to Aristotle, of whose shell-bearing polypi, the second is considered to be the Nautilus Pompilius ; the first species, the true Nautilus of the ancients, and to which Gualtieri gave the name Cyméium, is the Argonauta of Linneus. Although the shell of the recent Nautilus has long been commonly known, little information existed as to the animal, beyond that given by Aristotle, until a comparatively recent period. At the beginning of the last century the Dutch naturalist Rumph drew the attention of zoologists to the animal of the Nautilus; a description of which, illustrated by figures, he gave in his work ‘PD Amboinische Rariteitkamer.’ From Rumph’s description, which, however im- perfect, was more intelligible than his drawing, De Montfort gave an imaginary representation of the animal, wide of the truth, but which was adopted by Shaw. After the time of Rumphius not any additional information was procured until the arrival in England, in 1831, of aspecimen of the Nautilus Pompilius, taken by Mr. Bennett in Marachini Bay on the south-west side of the island of Erramonga, one of the New Hebrides. Itis true that in the preceding year MM. Quoy and Gaimard had published, in the ‘ Annales des Sciences Naturelles,’ an account of a portion of some unknown molluscous animal, which they supposed to be the Nautilus Pompilius, found near the island of Celebes; but the remains were too imperfect for satisfactory description, and, in fact, they have generally been attributed to a Heteropodous Mollusc, either Carinaria or Pterotrachea. The specimen brought over by Mr. Bennett was placed in the hands of Professor Owen, who in 1832 published his Memoir before referred to with minute anatomical descriptions and illustrations. In 1839 M. Valenciennes published an account entitled ‘ Nouvelles Recherches sur le Nautile flambé,’ taken from an individual transmitted to the Museum of Natural History at Paris. These two works afford ample information as to the animal, but it is unnecessary to enter into the details, a brief outline, sufficient for the present purpose, having already been given. Of the soft parts of the animals which inhabited the fossil shells, no trace has been found to assist the Paleeontologist, who must, therefore rely wholly on the calcareous remains for specific distinctions. As regards the tertiary species, these distinctions appear to be tolerably well defined ; and but little difficulty will be found in the determination of the species. The shell is smooth, spiral, and symmetrical ; suborbicular, or somewhat depressed, and more or less round on the ventral aspect; the margins of the aperture are smooth and simple ; the whorls are contiguous, and convoluted in a vertical plane, the last being the largest and concealing the rest, by which character it is distinguished from Planulites, the whorls of which are exposed. In some species the umbilicus is open; but more generally it is closed, as in the adult specimens of the recent V. Pompilius, by a deposition of nacreous or calcareous matter. The lines of growth are distinct, and in some species strongly marked, giving a somewhat striated appearance to the shell ; and they are reflected backwards, in which respect they differ from those of the Ammonitide, AA EOCENE MOLLUSCA. which are bent forwards. The chambers are separated by transverse partitions, more or less undulated ; and in one species, VV. Parkinsoni, they are distinguished by lateral angular lobes, resembling those of Aturia (Nautilus) zic-xac, and the margins are invariably simple and entire. The discs of the septa are perforated at the centre, or at parts more or less distant from the margins, but never at the margin, by a calcareous siphuncle, variable in size and generally discontinuous, that is, extending more or less into the preceding chamber, but not into the preceding siphuncular aperture. The chambers themselves increase in size to the last, which is sufficiently large to contain the whole of the animal; but the ratio of increase is apparently uncertain, and is influenced probably by the growth of the animal, which would, of course, depend on the supply of food and other circumstances. The fossil substances termed R/yncolites, which occur so frequently in the older formations, and which are generally believed to be the mandibles of some of the Tetra- branchiate Cephalopods, with whose remains they are associated, have been found both in the Paris basin and in the tertiary formations in Belgium; but I believe that as yet they have not been found in the Eocene strata of England. The specific characters in this genus are taken from the curvature of the septa, the general outward form of the shell, (which, in fact, determines the shape of the septum,) the position of the siphuncle and the condition of the umbilicus. With respect to the terms dorsal and ventral, it must be borne in mind that they are used in the following descriptions in a sense directly the reverse of that in which they have been generally applied. The Nautilus, in its normal position, rests upon, or creeps along the ground by means of, the free and expanded anterior portion of the mantle. In this position the back of the animal is against the penultimate whorl of the shell, and the ventral part is contained within the concavity of the dwelling-chamber. In the following descriptions, therefore, the term dorsa/ is used to designate the parts contiguous to the penultimate volution of the shell, and which have been generally, though incorrectly, described as ventral; and the term veztra/, on the other hand, will be applied to those parts on which the belly of the animal rested, and which hitherto have usually been termed dorsal. At present six species have been found in the tertiary strata of England, and they are confined to the older Eocene deposits. In the contemporaneous strata of the Paris basin two species occur, one of which is also found in Belgium ; but not either of them has as yet been found in England; and four species have been described by Sismonda and Michelotti, as occurring in the Miocene formations in Piedmont. Two of these last species are referred by those authors to existing species; but the accuracy of the identification is questioned. CEPHALOPODA. 45 No. 7. NAUTILUS CENTRALIS. Sowerby. Tab. III, fig. la—c. Navritus cenrrais, J. Sow. 1812. Min. Con. vol. i, p. 11, tab. 1, left-hand figure. = AUSTRALIS (by error for CENTRALIS). Defrance. 1825. Dict. des Sc. Nat. vol. xxxiv, p. 297. — ceNTRALIS. Wetherell. 1836. Philos. Mag. and Journal, vol. ix, p-. 465. = Bucktanvi.(?) Michelotti. 1840. Ind. rag. di alcuni Testacei de Cefal. foss. &e. Ann. delle Scien. del Regno Lomb.-Veneto, p. 4. — cENTRALIS. Morris. 1843. Cat. Brit. Foss. p. 182. — Pictet. 1845. Traité élément. de Paléont. vol. ii, p. 338. pas — Sow. 1849. Dixon’s Geol. Hist. &e. pp. 110, 121, tab. 14, fig. 28. NV. testé globosd, in aspectu ventrali rotundatd ; aperturd semilunari ; umbilicatd, umbilicis angustis, profundis ; septis extis concavis, simplicissinis, siphone central, minimo, continuo perforatis ; lobis dorsalibus latis, haud reflevis. The N. centralis, m the simplicity of the septa and the central position of the siphuncle, nearly resembles the recent Nautili. It is a very ventricose, almost a globose shell, much rounded on the ventral aspect; the aperture is bluntly lunate, nearly semicircular, and is rather more than twice as wide as it is long; the open umbilicus is narrow and deep ; the septa are concave outwardly, and simple, scarcely presenting any undulation or second curvature whatever; the dorsal lobes are broad, each being nearly one third of the width of the aperture, and they are bluntly rounded on their superior margins; the siphuncle is very small, central, or nearly so, and continuous. The lines of growth present broad undulations, and are strongly marked and decussated. Michelotti has described a Nautilus from the Miocene formations of the Colle de Tormo, in Piedmont, to which he has given the name Buchlandi. He quotes LV. centralis of Sowerby by the name JV. australis (an error into which he has fallen by relying on Defrance’s quotation), and he considers his shell to be identical with it, and, oddly enough, associates with it VV. zmperialis. The specific description given by this author agrees tolerably well with that of the present species; but I have not myself had any opportunity of comparing the Piedmontese with the English shell; and as Michelotti does not mention his having compared the two, and he appears to have trusted implicitly to Defrance, the accuracy of the identification must for the present be considered as doubtful. Mr. Wetherell, in his paper above quoted, gives this species and Naut. regalis as characteristic of the middle division of the three which he thinks might be made of the true London Clay. It occurs at Regent’s Park, Chalk Farm, Hyde Park, Richmond, Sheppy, and Bognor; itis also found, though very rarely, at Bracklesham Bay. The species does not appear to have attained a great size, the largest specimen not exceeding 3°7 in. in diameter, by 3°3 in. across. The figs. 1 and 2, Tab. III, are taken from specimens in the collection of Mr. Wetherell; fig. 3, from one in that of Mr. Sowerby. The form of the septum is shown by fig. 2, Tab. VIII. 46 KOCENE MOLLUSCA. No. 8. NAUTILUS REGALIS. Sowerby. Tab. IV. NaUTILUs REGALIS. J. Sow. 1823. Min. Con. vol. iv, p. 77, pl. 355. — _ Def. 1825. Dict. des Se. Nat. vol. xxxiv, p. 300. — — Weth. 1836. Philos. Mag. and Journ. yol. ix, p. 465. _ — Morris. 1843. Cat. Brit. Foss. p. 183. — — Pictet. 1845. Traité élément. de Paléont. vol. ii, p. 338. a — Sow. 1849. Dixon’s Geol. Hist. &c. p. 120. NV. Testa levigatd, sub-ventricosd, in aspectu ventrali compressa, obscure undulata ; apertura obtuse-ellipticd ; umbilicis obtectis ; septis simplicibus, concavis, utroque latere perparum undulatis, siphone sub-centrali perforatis ; lobis dorsalibus brevibus, rotundatis, haud refleais. The present species is distinguishable from the preceding by the closed umbilicus, and by its general form, which is less ventricose than that of JV. centralis. It is a smooth shell, flattened on the sides, and bluntly rounded, and obscurely undulated on the ventral aspect. The aperture presents a subquadrate appearance. The umbilicus is closed by a thickening of the lip, assuming the appearance of a solid axis to the shell. The septa are nearly simple, presenting on each side slight undu- lations, and the short, rounded dorsal lobes are deeply concave, and not reflected. In the young shell the septum is characterised by a conical depression placed on the dorsal margin close to the preceding whorl; as the shell enlarges this gradually decreases in size and depth, and ultimately disappears. It was of course moulded on a corresponding protuberance on the animal, probably an enlargement of the epithelial cincture. In some species the cavity is very deep. It was on this character that De Montfort, mistaking the depression for the mouth of a second siphuncle, founded his genus Bisiphites. The siphuncle is small and excentric. The lines of growth, like those of the preceding species, are decussated, and reflected backwards in broad undulations. The Nautilus regalis attained a large size. The specimen figured, for the use of which I am indebted to Mr. Dixon, measures 9°5 in. in diameter, by 5 in. across. The species occurs at Islington, Regent’s Park, Chalk Farm, Hyde Park, and at Bognor. It appears to have been one of the most common of the English Kocene Nautili. The septum is represented at Tab. VIII, fig. 5. No. 9. NAvTILUS URBANUS. Sowerby. Tab. III, fig. 2 a—é. NAUTILUS URBANUS. J.D. C. Sowerby. 1843. Min. Con. vol. vii, p. 36, pl. 628. _ = Morris. 1843. Cat. Brit. Foss. p. 183. — — Pictet. 1845. Traité élement. de Paléont. vol. ii, p. 338. NV. Testd discoided, in aspectu ventrali rotundatd, et obscuré undulata ; umbilicata ; apertura subquadratd, elongatd ; septis oblongis, concavis, in utroque latere leniter undulatis et siphone excentrico perforatis ; lobis dorsalibus perbrevibus, oblique truncatis, haud reflexis. CEPHALOPODA. 47 A flat discoidal shell, rounded on the ventral aspect, and presenting obscure undulations similar to those which characterise JV. regalis. The aperture has an elongated, subquadrate shape; the umbilicus is narrow; the septa concave, and slightly undulated; they present on each side, in a line with the preceding whorl, a slight depression, which appears to be the first indication of the lateral lobes so fully developed in the WV. Parkinsoni; the siphuncle is excentric ap- proaching the dorsal margin; the dorsal lobes are short, very slightly concave, obliquely truncated, and not recurved. The lines of growth are prominent, and decussated more strongly than those of the two preceding species, and their undula- tions are broad and shallow. The Nautilus urbanus is distinguishable from JV. centralis by its flatness, and the greater length of its aperture; and from JV. regalis by its open umbilicus, the truncated extremities of the dorsal lobes of the septa, and its discoidal shape. It is a very rare shell. The figures 2a, 24, Tab, III, are taken from the shells drawn in ‘Mineral Conchology, the only specimens with which I am acquainted. The larger one, belonging to Mr. Sowerby, was found in excavating St. Katharine’s Docks, near the Tower of London; the smaller one forms part of Mr. Bowerbank’s collection, and was obtained from Sheppy. The size of the larger individual figured is 7°4 in. in diameter, by 3°4 in. Fig. 4, Tab. VIII, represents the septum. No. 10. NAUTILUS IMPERIALIS. Sowerby. Tab. V. NAUTILUS IMPERIALIS. J. Sow. 1812. Min. Con. vol. i, p. 9, tab. 1, upper and right-hand figures. _ -- Defrance. 1825. Dict. des Sci. Nat., tome xxxiv, p. 297. — — Wether. 1836, Philos. Mag. and Journ. vol. ix, p. 465. — Bucxuanpt. Michelotti. 1840. Indice ragionato, &e. p. 4. _ IMPERIALIS. Morris. 1843. Cat. Brit. Foss. p. 182. — _ Pictet. 1845. Traité élément. de Paléont. vol. ii, p. 338. _ _ Sowerby. 1849. Dixon’s Geol. Hist. &e. pp. 110, 120. N. Testé spheroidale ; umbilicatd, umbilicis angustis, profundis; apertura sub- ellipticd, semilunari ; septis undatis, siphone mediocri dorso-excentrali perforatis ; lobis dorsalibus latis et perparum reflexis. This species is easily distinguished from the JV. centralis by the excentric position of the siphuncle, as well as by the broad and reflected extremities of the dorsal lobes, which form, as it were, an axis to the shell. Its orbicular form, the lunate shape of the septa, and the recurved dorsal lobes, distinguish it as clearly from JV. rega/is and NV. urbanus. 48 EOCENE MOLLUSCA. The Nautilus imperialis is a somewhat globose shell, rather narrow on the ventral aspect, whence the aperture assumes a sub-elliptical form; the umbilicus is small and deep. It is well displayed in the large figure, Tab. V, taken from a specimen in Mr. Bowerbank’s collection, but generally, it is found open only in young shells; in the larger specimens it is usually filled with pyrites or indurated clay. The septa are deeply concave, and present a gentle undulation on each side; the dorsal lobes are very broad, inflected towards the axis, and obliquely truncated on the inferior margins. The siphuncle is moderately large, and excentric, being placed on the dorsal side of the centre of the disc. It appears to vary in its position, gradually becoming more distant from the dorsal margin as the shell enlarges. The lines of growth are reflected backwards in a deep narrow wave, and in the specimens I have seen are not decussated as in the three preceding species. In the shell described by Michelotti under the name WV. Buchklandi, and with which he has associated the present species, the siphuncle is central; and that character is, in fact, the reason assigned by him for considering his shell to be identical with NV. centralis as well as with NV. imperialis. Whether the alleged identification of JV. Bucklandi with N. centralis be correct or not, it is obvious that the Piedmontese shell cannot be referred to the present species. Defrance states that the JV. cmperialis did not appear to differ from JV. centralis, and Michelotti has, in fact, relied implicitly on that author; he has even copied the mistake made in quoting JV. centralis as NV. australis. The JV. imperialis attained a very large size; a specimen from Sheppy in the Museum of the Geological Society measures 12 inches by 8°75 in. across. It appears to have been widely spread, being found at Highgate, Hornsey, Brentford, Sheppy, Cuffell near Basingstoke, Clewett’s Green, Newnham, Bognor, and Bracklesham. The form of the septum is shown in Tab. VIII, fig. 1. No. 11. Nautitus Sowersyl. /Vetherell. Tab. VI. Navritus Sowersyl. Weth. 1836. Phil. Mag. and Journ. vol. ix, p. 466. — -- Morris. 1843. Cat. Brit. Foss. p. 183. —_— _ Sow. 1843. Min. Con. vol. vu, p. 35, pl. 627, fig. 1-3. — _— Sowerby. 1849. Dixon’s Geol. Hist. &c. p. 121, tab. 14, fig. 28. N. Testa levigatd, lenticulari, ventrali aspectu anguste rotundatd ; umbilicata, apertura sub-triangulari ; septis profunde concavis ; siphone continuo, prope margines dorsales posito, perforatis ; utroque latere late undulosis et sublobatis ; lobis dorsalibus elongatis, valde reflexis, oblique truncatis. The WV. Sowerby: is an exceedingly well-marked species. Itis a smooth, discoidal, convex or rather lenticular shell, somewhat resembling in shape the Dax form of CEPHALOPODA. 49 Aturia (Nautilus) zic-zac, but it is narrower towards the margin, which circumstance . gives a triangular form to the aperture. The septa (Tab. VIII, fig. 3) are very concave, and present on each side a broad undulation, with a deep sinus-like depression caused by a lateral lobe, more developed in this species than in JV. wrbanus, although not attaining the size and importance of that which distinguishes V. Parkinsont. The dorsal lobes are much recurved and obliquely truncated; the siphuncle is moderately large, placed very near to the dorsal margin, and continuous. The strice of growth towards the middle are suddenly bent backwards in deep undulations. This species, which attained a size of 10 inches in diameter by 4°2 in. across, was first obtained by Mr. Wetherell from the tunnel made at Chalk Farm for the Birmingham Railroad. It has also been found in the cuttings now in progress between Whetstone and Barnet for the Direct Northern Railroad, and it occurs at Sheppy and at Bognor, where it is very common. No. 12. Nautitus ParKinsonr. F. £. Edwards. Tab. VII. Navriiire. Parkinson. 1811. Organic Remains, p. 105, pl. 7, fig. 15. LV. testé discoided, apertura elongato-elliptica, parvetibus convexis ; umbilicis (?) ; septis exttis concavis, in utroque latere angulariter lobatis, siphone, prope margines dorsales posito perforatis ; lobis lateralibus brevibus, subtriangularibus, mucronatis ; lobis dorsalibus latis, perparum concavis, ad extremitates attenuatis, reflexis. Parkinson, in his work above cited, described the remains of a Nautilus, purchased by him at the sale of Dr. Menish’s collection. These remains, which consist of the casts of three chambers, afterwards came into the possession of Mr. Sowerby, who has placed them at my service. Parkinson was ignorant of the locality whence they came; but from their mineralogical character, the matrix being, in fact, the substance known as cement-stone, it was supposed that they were found at Harwich. Lately the Rev. Thomas Image, of Whipstead, near Bury St. Edmunds, has forwarded to me for examination similar remains, unquestionably obtained at Harwich, and consisting of the casts of two chambers, rather smaller than those in Parkinson’s specimen, and in a matrix precisely similar. The question, therefore, as to the locality of Parkinson’s specimen is set at rest. These remains are particularly interesting, from the circumstance that in them the angularly-lobed septum which characterises Aturia (Nautilus) zic-xac, and in that shell is accompanied by a strictly dorsal siphuncle, is associated with one which, although very excentric, is still so truly discal, as to prevent the shell being removed from the present genus. The form of the septum is a good specific character, but it cannot be relied upon as a generic distinction. The Nautilus Parkinsoni, therefore, although in general appearance it closely resembles 4¢wria, must, in fact, from the position of the siphuncle i “4 50 EOCENE MOLLUSCA. be considered as an aberrant Nautilus, connecting that genus with Aturia, and leading through the Clymenid@ into Goniatites and Ammonites. The JV. Parkinsoni is a discoidal shell, with regular convex sides, and an elongated elliptical aperture. The specimens do not exhibit the condition of the umbilicus. The septa are outwardly moderately concave, with angular lobes on each side; the dorsal lobes are very broad, somewhat concave, rounded at the extremities, and reflected, although not much, towards the axis; the lateral lobes are short, wide at the upper extremities, and they taper rather suddenly; their inferior margins are nearly straight, but the superior margins present a deep sinus. The siphuncle is moderately large, and is placed on the dorsal part of the septal disc, half way between the centre and the margin. So far as the general character can be ascertained, the siphuncle does not appear to differ from that of JVawtilus, and certainly does not present any analogy with the wide trumpet-mouthed funnel which distinguishes Aéuria. This species appears to have attained a greater size than any other of the tertiary ‘Nautili; the largest chamber in Parkinson’s specimen measures seven inches in breadth, and nine inches in length; and this chamber was not the last, and conse- quently not the largest. Family—CiLYMENIDE&. AcaNnID&. Pictet, Deshayes, D’ Orbigny. Adopting the opinion of Von Buch, that the position of the siphuncle is the principal, if not the only, character by which the Tetrabranchiate Cephalopods can be divided into families, it becomes impossible to include those genera in which the siphuncle is placed on the dorsa/ margin, either among the Nautilide, in which it is central or excentric, or among the Ammonitidz, in which it is placed on the ventral margin. The only genera at present known to possess a strictly dorsal siphuncle, are Clymenia, Munst. (Endosiphonites, Ansted), and Aturia, a genus proposed by Bronn for the Nautilus Aturi, Basterot (V. zic-zac, Sow.) In fact, these genera have already been considered by MM. d’Orbigny, Deshayes, and others, to form a subdivision of the Nautilidz, to which those authors have applied the name Aganidee, founded on a genus proposed by De Montfort for a shell from the mountain limestone. This shell, however, possessed a ventral siphuncle, and belonged to the genus Goniatites.* The name Aganide, therefore, cannot with propriety be retained as a family name for genera characterised by a dorsal siphuncle; and I have adopted, in lieu of it, the name Clymenide, founded on Munster’s genus. * The shell figured and described by De Montfort as Aganides is, I believe, the Gontatites sphaericus of Sowerby. CEPHALOPODA. 51 The septa in the Clymenide are distinguished by lateral rounded or angular lobes ; but the angular form is not peculiar to the family; since, as we have already seen, it is found in Nautilus Parkinsoni, a species which, possessing an excentric siphuncle, must*be considered as merely an aberrant form of Nautilus ; and the separation of the Clymenide will depend entirely on the siphuncle being placed on the dorsal margin. The two genera which belong to this family are distinguished chiefly by the mode of involution of the shell; the whorls in Clymenia being exposed, while in Aturia the last whorl conceals the rest ; they therefore bear to each other the same relation which Planulites bears to the true Nautilus. Genus 5th. ATuRIA.* Bronn, 1837. Gen. desc. 4. testi discoided vel subventricosd, spirali, multiloculari, parietibus simplicibus ; anfractibus contiguis, ultimo alios obtegente ; umbilicis clausis ; septis trans- versis, numerosis, extis concavis, utroque latere angulariter lobatis et parte dorsali, magnd siphone infundibuliformi, marginibus positd, retro prolongatis ; marginibus simplicibus. Shell discoidal or subventricose, spiral, multilocular, sides simple: whorls con- tiguous, the last concealing the others; the umbilicus closed; septa transverse, numerous, concave outwardly, with an angular lobe on each side, and having the dorsal part prolonged backwards, forming a large, marginal, funnel-shaped siphon ; margins of the septa entire. The angularly-lobed septum which distinguishes Nautilus Parkinsoni also forms a prominent character in the well-known Highgate fossil, Naut. ztc-zac, figured and described by Mr. Sowerby in the first volume of the ‘Mineral Conchology.’ Bronn, in his description of the Dax shell Nautilus Aturi (Bast.), which he considered to be distinct from JV. zic zac, suggested the propriety of forming a sub-genus, to be called Aturia, for the reception of those tertiary Nautili in which, according to the sub- generic description given by him, “the siphon is sub-ventral (i. e. sub-dorsal), and the septa have a deep, narrow, lancet-shaped flap on each side.” ‘The siphuncle, however, in the Dax shell, on which the genus is founded, is, in fact, strictly marginal; it is, as Bronn himself describes it, a prolongation backwards of the dorsal part of the septum, in the shape of a wide-mouthed funnel, extending quite across the preceding chamber, and deeply into the mouth of the preceding funnel. As this funnel-shaped siphon decreases in diameter, the dorsal paries gradually recedes from the margin, and the intervening space is filled up with a calcareous deposit. The siphuncle, therefore, will in some parts of its extent appear to be sub-marginal only : whereas the mouth of the * Etym. Aturrus ved Aturus—the River Adour. 52 EOCENE MOLLUSCA. siphuncle, by which only the position can be determined, is perfectly marginal. The Nautilus Aturi, which I consider to be identical with Nautilus zic-zac, is the type of Bronn’s genus, and I therefore retain the name proposed by that author, although I do not assent to the accuracy of his generic description. The genus Clymenia, proposed by Count Munster for certain Nautiliform remains occurring in the transition limestones of Fichtelgebirge, presents nearly the same characters as those assigned by me to Afuria; except that in Clymenia the whorls are exposed, and the siphuncle is described as narrow; whereas in Afuria the last whorl conceals the others, and the siphuncle, at least in 4. z/c-zac, the typical species, is of oreat size. The genus appears to have been confined to the tertiary epoch, and it is widely diffused. It occurs in the Eocene formations of England, France, Belgium, and Germany ; in the Miocene deposits in the basins of the Gironde, in Italy, and in Malta. It is also found in the Eocene formation in Clarke county, Alabama, (U.S.), and Conrad* mentions a cast from the contemporaneous formation near Long Branch, New Jersey, resembling Nautilus (Aturia) zic-zac, but more compressed, and which he has referred to De Montfort’s genus Pelagus, and has named P. Vanuxemi. De Montfort’s Pelagus, however, is described as having “cloisons lobées, persillées, dentelées, &c.” The position of the siphuncle is not mentioned in De Montfort’s text; but in the figure he has given it is placed on the ventral margin. The shell, therefore, on which the genus Pelagus is founded is an Ammonite, and the species constituting the present group cannot be associated with it. No. 13. Aruria zic-zac. Broun. Tab. IX, fig. la—s. Var.a. Navriius z1c-zac. Sow. 1812. Min. Con. vol. i, p. 9, pl. 1, fig. 3. Ammonites Waprprert. Van Mons. 1833. L’Institut. 1833, p. 272. — — — 1834. Bull. de lAcad. de Brux. tome i, No. 17, pp. 113, 118. Navritus Desuayest1. De Koninck. 1834. Notice sur un Moule pyriteux du Naut. de Desh.; Bull. Soc. Géol. de France; t. iv, p. 437. — — Nyst. 1835. Rech. sur les Coq. foss. de la Prov. d’Anvers, p- 35, No. 52. = — De Koninck. 1837. Desc. des Coq. foss. de l’Argile de Basele, p. 1. — Aturt. Bronn. 1837. Leth. Geog. vol. ii, p. 1123, pl. 42, fig. 17a—e. -- z10-ZAC. Desh. 1837. Desc. des Coq. foss. des Env. de Paris, vol. ii, p. 765, pl. 100, figs. 2, 3. CryMenta ztc-zac. Michelotti. 1840. Amnal. Scient. reg. Lomb. Venet. p. 6. * Conrad’s “ Observations on the Eocene formation, and description of one hundred and five new fossils of that period, from the vicinity of Vicksburg, Mississippi,” published in the Journal of the Academy of Natural Science of Philadelphia. CEPHALOPODA. 53 Navtitus zic-zac. Nyst. 1843. Bull. Soc. Géol. de France, vol. xiv, p. 452. _ _— — 1843. Desc. des Coq. foss. &c. des Terr. tert. dela Belgique, p- 644, pl. 46, fig. 4. — Morris. 1843. Cat. Brit. Foss. p. 183. AcanrpEs Desnayesit. Sismonda. 1847. Method. Anim. invert. Pedemontii Foss. p. 57. — iG-zaG. Pictet. 1845. Traité élément. de Paléont. Vol. ii, p. 341. Naurrius (Ctymenta @) z1c-zac. Sow. 1849. Dixon’s Geol. Hist. &c. p. 109, pl. 8, fig. 19. Var. 3. Navrite pe Dax. De Monéf. 1802. Buffon de Sonnini Moll. vol. iv, pp. 240, 252, pl. 46, fig. 1. Navritus Pompiius. Lam. Ann. du Mus. vol. y, p. 181. — —_ — 1822. An. sans Vert. vol. xvi, p. 634. — DesnAyesit. Defr. 1825. Dict. de Hist. Nat. vol. xxxiv, p. 200. — Aturt. Bast. 1825. Desc. des Coq. foss. des Env. de Bordeaux, p. 17. Orputites z1c-zac. De Blainv. 1825. Man. de Malae. p. 387. Navritus (AcaNntDes) Aturt. D’Orb. 1825. Tab. method. de la Classe des Céph. p. 71. — Syrno. Buckl. 1836. Bridgw. Treat. vol. i, p. 357, pl. 46, figs. 1-4. — — Grateloup. 1838. Cat. des An. vert. et invert foss. du Basin de la Gironde, p. 28. Acanipes Arurt. Pictet. 1845. Traité element. de Paléont. Vol. ii, p. 341. ~ A, Testd ventricosd, levigatd ; umbilicis clausis ; septis concavis ; lobis lateralibus angustis, acutis ; dorsalibus valde recurvis ; siphone magno, continuo, buccineforme. Var. B. Zestd compressa, sub-discoided ; septis profundé concavis, lobis dorsalibus angustioribus. Shell ventricose, smooth ; umbilicus closed; septa concave; lateral lobes narrow, pointed ; dorsal lobes much curved ; siphuncle large, continuous, trumpet-shaped. There are scarcely any tertiary remains which have excited so much attention as the present; not merely because the species is widely diffused, but because it presents an intermediate form between the Nautili and the Ammonites ; and few fossils have been referred to more genera, or have been distinguished by a greater number of specific names. The Aturia zic-zac was first described by Mr. Sowerby, sen., as Nautilus zic-zac, from a specimen which was found on forming the tunnel of the Highgate Archway. Several years afterwards M. Defrance described a specimen from the Paris basin, and pointed out the differences which, in his opinion, rendered it difficult to refer the species to the genus WVawtilus. M. Defrance considered the fossil described by him as distinct from the /V. 2¢c-zac, and gave to it the specific name Deshayesit. Subsequently Basterot described the well-known Dax fossil, which he named Naut. Atur’, and with which he considered the Nawt. zic-zac to be identical. M. d’Orbigny and Sig. Sismonda, not regarding the dorsal position of the siphuncle, but relying on the angular lobes which characterise the septa, have referred the shell in question to De Montfort’s Ayanides, a genus which, as has been before stated, was founded on a Goniatite from the mountain limestone. Michellotti, on the other hand, has considered 54 EOCENE MOLLUSCA. the present remains as forming part of Munster’s Clymenia, a genus distinguished by its having the whorls exposed. The Aturia zic-zac is a smooth, involute shell, more or less ventricose or depressed ; the septa are outwardly deeply concave; and, owing to the regular curve in which the dorsal lobes are reflected towards the axis of the shell, they present, when viewed sideways, some resemblance to the letter S; the lateral lobes are more or less narrow, and taper rather suddenly towards the inferior extremity, which extends nearly to the preceding septum; but they are without the sinus which characterises the lateral lobes of Naut. Parkinsoni. The English shells are generally either casts in, or filled with pyrites, and it is difficult to ascertain the character of the siphuncle from them ; but in the Dax shells, in which the calcareous siphon is frequently well displayed, it presents a structure widely different from that of the Nautilus. The dorso-marginal part of the septum, as I have before observed, is prolonged backwards in the form of a wide trumpet-mouthed funnel, which extends not only into the mouth of the funnel formed by the preceding septum, but along the preceding siphuncle almost to the floor-of the third preceding chamber (see Tab. IX, fig. 2c). The calcareous siphuncle, therefore, is, in fact, a continuous tube of considerable thickness, composed of portions of two distinct tubes; and within this is contained a soft, friable, calcareous sheath, which commences near the extremity of the funnel, where it touches the preceding funnel, and extends to the end of the preceding funnel, to the imterior surface of which it forms a sheath. Although, owing to the thickness of the walls and the presence of the calcareous sheath, the actual tube within which the membranous siphuncle was contained is not so capacious as might be expected from its external appearance, it is yet considerably larger than that of any of the tertiary Nautili; and indeed it is of such size and importance as fully to justify the name Sypho, which Grateloup has given to the Dax shell. The siphuncle in the English specimens, so far as its character can be ascertained, appears to correspond exactly with that of the Dax shells. . Great diversity of opinion has existed, and, in fact, still exists, as to the identity of the Dax shell with the Nawt. xic-zac of Sowerby. The differences which have been relied on for the separation of the two appear to me to result from the more compressed form of the Dax shells; the specimen figured by Mr. Sowerby, although described as “flattish,” being ventricose, and the outline of one of the septa drawn below the shell conveying the idea of greater fulness than in fact characterises the fossil. M. Deshayes, who compared the Dax shells with specimens as well from the Paris basin as from Belgian and English localities, expressed an opinion that the differences were sufficient to form, if not two species, at least two well-marked varieties. I have not myself had an opportunity of examining any French or Belgian specimens; but, through the kindness of Mr. Sowerby, Mr. Bowerbank, and Mr. Wetherell, who have afforded me the use of their specimens, I have before me a series of shells from Sheppy and the CEPHALOPODA. 55 neighbourhood of London, including the identical specimen figured by Mr. Sowerby. Confining myself to external characters only, two distinct forms occur in this series, the differences in which, although they may require a separation into varieties, are not sufficient, in my opinion, for specific distinctions. In the first variety, which is the true Naut. zic-zac, figured in ‘ Mineral Conchology,’ and which I have therefore taken for the typical form, the shell is ventricose, the greatest width being little less than half the diameter; it is moderately round on the ventral aspect, and the aperture is a somewhat elongated ellipsis. In the other variety (3) the shell is more compressed, almost discoidal ; and consequently it is narrower on the ventral aspect; the dorsal lobes are not so broad, and the aperture is of a more elongated oval form. The French, Belgian, and German shells correspond apparently with the first, the typical form, and the Dax shells agree closely with the second variety. Michellotti has used for the Piedmontese specimens the specific description given by M. Deshayes ; but he adds, that “they present some trifling differences from the Paris specimens, as do the latter from the London and Bordeaux shells.” As, however, the Piedmontese shells are described as typical form, although we should naturally expect to find the Dax type continued in the Miocene formations of the Colle de Torino. The Aturia zic-zac also occurs in the Miocene deposits in Malta, and the specimens which I have seen from that locality present the depressed form of the Daxshells, with which they agree in other respects. Mr. Sowerby possesses a series of casts from the Eocene formation in Clarke County, Alabama, of a species which approaches very near to the typical Afuria zic-zac ; the chief distinction appears to be in the form of the lateral lobes, which in the American shell extend quite to the margin of the preceding septa, and have their extremities inflected towards the axis, and present the deep sinus which characterises the lateral lobes of Nawt. Parkinsoni. The siphuncle is very large, and corresponds with that of 4. 27c-zac. Conrad describes his Pelagus Vanuxemi as more compressed than the latter shell, and he adds that “the angles of the septa appear to be in contact near the periphery.” This appearance, which is attributable to the length of the lateral lobes, and is represented in the figure given by Conrad by a continuous line running parallel with the periphery of the shell, is also found in the Alabama specimens, of which Conrad’s shell is possibly only a compressed variety. The typical form, which is represented at Tab. IX, fig. lz, 14, drawn from the original specimen figured in ‘ Mineral Conchology,’ for the use of which I am indebted to Mr. Sowerby, is found at Highgate, Sheppy, and Bracklesham Bay. The variety B, which corresponds with the Dax shells, was obtained from the railroad cutting at Chalk Farm, and from the well sunk for the use of the Orphan School, at Haverstock Hill, “ventricose,” they must for the present be referred to the 56 EOCENE MOLLUSCA. near Hampstead. The specimen figured (Tab. IX, fig. ly, 1/,) is from the former locality ; it is the one drawn by Mr. Charlesworth in the ‘ Magazine of Natural History,’ vol. i, (new series,) p. 533, and forms part of Mr. Wetherell’s valuable collection of fossils from Highgate and the neighbourhood. The English shells are apparently young; they are much smaller than the Dax specimens, the largest I have seen cannot have exceeded 1:6 in. in diameter. PRINTED BY C. AND J. ADLARD, BARTHOLOMEW CLOSE. VEG Za (Ch: a l20 | ote Ko). PED. A MONOGRAPH OF THE MOLLUSCA FROM THE EOCENE FORMATIONS OF ENGLAND. ORDER—PULMONATA. CuviER. PNEUMOBRANCHTATA, Lamarck. PuLMoBRANCHIATA, De Blainville. PULMONIFERA, Fleming. Tue Molluscs forming this order breathe the free air by means of a chamber termed the pulmonary sac or cavity, placed beneath the dorsal surface of the anterior part of the mantle, and communicating with the atmosphere by a lateral opening, which can be dilated or contracted at the pleasure of the animal. The roof and walls of this chamber are lined with a network of pulmonary vessels, by which the blood is exposed to the air, and the renewal of this vital fluid is effected by movements of the floor of the chamber, analogous with those of the diaphragm. The Pulmonated Molluscs are furnished with eyes, which are either placed at the anterior extremities of two elongated cylindrical peduncles, or seated in the head of the animal. Most of the genera in which the eyes are pedunculated, are also furnished with shorter cylindrical tentacula, placed beneath the peduncles, but in some few instances these appendages are wanting. In the genera in which the eyes are sessile, the animal is furnished with two sub-cylindrical or compressed tentacles only. The sessile eyes are variously placed; in some genera they are seated at the inner sides of the bases of the tentacles ; in others at the outer sides ; and in others on the frontal disc. The peduncles and tentacles are both contractile, and in by far the greater number of genera they are also retractile, that is, capable of being withdrawn under the skin. They are eminently sensitive organs of touch. The head is well developed, and the mouth is provided with an apparatus 8 58 EOCENE MOLLUSCA. consisting of a horny dentated plate, placed transversely across the upper part, and the sharp outer edge of which forms, as it were, the upper jaw. The cavity of the mouth is furnished with a thin cartilaginous tongue, the anterior extremity of which is of a flattened spoon-like form, and which plays against the edge of the horny plate, answering the purpose of an under jaw. The remainder of the tongue is rolled up into a tube closed at the end, and thickly covered with teeth, distributed in transverse rows of various forms. The number of these teeth is almost incredible, amounting, in one of the English slugs (Limar mazximus) to nearly 27,000, and ranging in several of the snails from 10,000 to upwards of 20,000.* A dentition of a similar character prevails among the Branchiated Gasteropods; and Professor Lovén has proposed the employment, for the purposes of classification, of characters taken from the form and arrangement of the teeth. The free air-breathing Molluscs are, in some few instances, viviparous, but, for the most part, they are oviparous. The eggs are either enveloped in a skin, or are covered by a hard calcareous shell, which, among the larger Bulimi and Achatine, is sometimes of considerable size. The larvee are in all cases shaped like the parent. The generative organs present various modifications; in some genera the animals are unisexual; but more generally they are hermaphrodite. These Molluscs are, with few exceptions, provided with hard calcareous shells, which are sometimes either internal or partly concealed beneath the mantle, but more generally are external, and large enough to contain the whole, or nearly the whole, of the animal. In some genera the foot of the animal is provided with a calcareous or horny operculum ; in others the animal is without this appendage, and in the genus Clausilia, the purpose of the operculum is answered by a peculiar apparatus termed the clausium. The external shells present many modifications in the proportions and conditions, as well of the spire and volutions, as of the aperture and columella. Certain of these forms are accompanied by corresponding peculiarities of organisation, and the genera which have been established for their reception may be considered types in this order ; such are the genera Helix, Bulimus, Pupa, Succinea, Limnzea, Physa, Planorbis, Cyclostoma, Helicina, Auricula, &c., and the Palzontologist will have little difficulty in distinguishing them. Other genera, however, have been proposed from time to time on characters taken from modifications of these typical forms; but a more intimate acquaintance with the anatomy of the animals has latterly induced great caution in the admission of these genera; since, in many cases, the Malacologist, after the most careful investigation, has failed to detect any peculiarity of organisation corresponding * Fora more detailed account of the oral apparatus, the reader is referred to Mr. W. Thompson’s highly interesting ‘Remarks on the Dentition of British Pulmonifera,”’ in the ‘Annals and Mag. of Nat. Hist.,’ 2d series, vol. vii, p. 86. + This is the case with some species of Helix, and with several species of Bulimus, for which Férussac, on this ground, proposed the genus Partula. PULMONATA. 59 with the modifications of the shell. In the extensive family of the Helicide, most especially, has this occurred, and many of the genera ‘thus formed are consequently either wholly rejected, or received provisionally until it is ascertained by further examination whether or not there is anything except merely artificial characters to support them. The Gasteropods forming this order are all phytophagous. They are very widely spread, being found in almost all parts of the earth, but they principally abound in warm or tropical climates, where the largest species occur. They are, for the most part, inhabitants of land, but many live in water, coming to the surface for respiration ; of those which live in water, the greater number inhabit ponds, running streams, or stagnant waters, but some few are marine animals, frequenting the shallow sea near the shores, or salt-water marshes. Two distinct forms of the opening by which the communication between the pulmonary sac and the external air is kept up, are presented; and as each appears to be accompanied by corresponding peculiarities of organisation, Mr. Gray has availed himself of them for dividing the order into the two sub-orders, Adelopneumona and Phaneropneumona.* In the first division the communication is through a lateral orifice formed by the edge of the mantle, which, except at that part, is united along the left side of the animal; in the second division the edge of the mantle is free or detached along the nape, leaving the pulmonary cavity open. ‘The animals comprised in the first division are all hermaphrodite, and without an operculum ; while, on the contrary, those which form the second division are unisexual and operculated. The genera constituting this order had previously been divided, according to their habitats, into terrestrial and aquatic (¢erricola and aquatica of Dr. Fleming); a mode of distribution which brought together animals presenting important zoological differences. This principle of subdivision may, however, be used with convenience in the Adelopneumona, and Mr. Gray has, in fact, divided that sub-order into the three sections, Geophila, Limnophila, and Thalassophila, the last two representing the aquatica of Fleming.t Mr. Webster many years ago, (‘ Geol. Trans.,’ vol. ii,) noticed the occurrence in the Purbeck beds of fossils resembling fresh-water shells, and in the Museum of Practical Geology is a series of fossils from that formation, comprising Limneea and Planorbis. Fossil remains, referred to the genus Avricula, have also been found, according to M. Nyst, in the chalk formation in the department of the Aube in France. In the * Etym., AdnAos, (hidden, concealed,) and gavepos, (open, exposed,) prefixed to rvevpwy, (the lungs.) These sub-orders correspond with the divisions inoperculata and operculata, proposed by Férussac, and adopted by Dr. Turton, M. Rang, and others, but as the names used by Mr. Gray express modifications of the respiratory apparatus, which forms the character of the present order, I have adopted them, although the words operculata and inoperculata are preferable from their simplicity. + Etym., yea (land), Acuxn (a pool or marsh), and @adacon (the sea), respectively prefixed to guXos (loving). 60 EOCENE MOLLUSCA. fresh-water deposits of the Eocene epoch, remains of numerous species belonging to various of the land and fresh-water genera, constituting this order, occur in abundance. These species are, for the most part, without any living analogue, but some few occur which appear to be identical with species still in existence. I believe that, as yet, remains of land inhabiting genera have not been found below the Eocene formations. It must not, however, be assumed from that circumstance that these latter forms of animal life date their existence with the Eocene Epoch. The older formations with which Geologists are at present acquainted, are, with the exception of the Wealden group and the Coal-measures, of marine origin; and the preservation in them of the remains of land-shells would be due only to accidental circumstances. Individuals might occasionally be transported by rivers or currents of water into estuaries, or be swept away by an irruption of the sea. To such a cause is to be attributed the presence of a specimen of Bulimus ellipticus, found by Mr. Wetherell in the London Clay at Primrose Hill; but the number deposited in the bed of the deep sea by the agency of such casualties, must necessarily be small, and it need not excite surprise that their remains have not occurred in the older formations. Sus-Orper—ADELOPNEUMONA (Gray), INOPERCULATA (Férussac). Sect. a. Terricoia, Fleming. GropuHita, Férussac. Family—HE.IciDz&. Genus 6th. Henix. Linn., 1758; Brug., 1792; Lam., 1801. Shell turbinated, orbicular, sub-globose, or depressed; spire more or less elevated, with several convex whorls, generally smooth; the last often large and ventricose ; aperture entire, transverse, oblique, lunate, or semi-ovate, impressed by the prominent part of the body whorl, and sometimes furnished with one or more lamelliform teeth ; peristome confluent with the columella, generally thickened internally, or having the edge reflected, especially on the side covering the umbilicus ; without an operculum. Notwithstanding that in Lamarck’s time but little was known of the comparative anatomy of the animals belonging to this family, we must concur in the regret expressed by M. Deshayes (2d edit., ‘Hist. Nat.,’ &c.) that that illustrious naturalist did not attempt a systematic arrangement of the numerous species forming this genus. A much more intimate knowledge of the anatomy of the animals has since been acquired; and it appears that, although the shells present a great variety of forms, differences of organisation of importance sufficient to justify the separation of genera to receive them, do not exist, or, at all events, have not been observed in the animals. This strong general resemblance extends, in fact, to the whole of the PULMONATA. 61 Helicidee, and induced M. de Férussac to arrange the different genera as sub-genera merely of the typical genus Helix. The present genus, as defined by Lamarck, embraces considerably more than a thousand living species; and may well be considered to be “deserving of subdivision, were it only to assist the student in the difficult task of investigation.” Very many genera and sub-genera (amounting, including the synonyms, to nearly two hundred,) have, in fact, been proposed from time to time by different authors; but being nearly all founded, more or less, on conchological differences, they are, with few exceptions, rejected by the advocates of a strictly natural arrangement. M. Deshayes, one of the most able advocates for a system of atfrangement dependent on anatomical structure, admits the convenience of having recourse to artificial divisions in this genus in which it is impossible to form natural groups; and suggests that the Helices may be classed, by the form of the shell, in four sections, consisting of the planorbular species, (Zonites, Montfort; Helicella, Lamarck,) the globose species, (4cavus, Montfort, ) the carinated species, (Jéerus, Montfort ; Carocolla, Lamarck,) and the trochiform or turbiniform species (Pefasia, Beck; Geotrochus, Swain.): and that these sections may be again subdivided into groups, according as the species are or are not umbilicated, have the aperture simple or reflected, or are or are not furnished with teeth. The fossil Helices are more numerous than might be expected with respect to land- shells. Many extinct species, from the Freshwater deposits of the Paris basin, have been described by MM. Brogniart, (‘Ann. du Mus.’ vol. xv, p. 378,) Deshayes, (‘Descr. des Coq. Foss.,’ &c., vol. ii,) Matheron, (Ann. des Sci. et de ’Indust. du Midi,’ vol. ii,) Michaud, (‘ Guerin’s Mag. de Zool.,’ 1837,) De Roissy, (‘ Guerin’s Mag. de Zool., 1839,’) and Melleville, (( Mém. sur les Sables Tert. Inferieurs du Bassin de Paris,’ p. 45;) and from the contemporaneous Freshwater formations in Germany by MM. Zeiten, (‘ Petr. Wut., tab. xxix and xxxi,) Steininger, (‘ Bull. Soc. Géol. de France,’ vol. vi,) Deshayes, (‘ Ency. Méthod. Vers.,) and Pusch, (‘ Polens. Pal.,’ p. 94.) One species only, 1. globosa, has as yet been described from the synchronous deposits in England; to this I am enabled to add eight species, one of which is identical with an existing species, HZ. Jabyrinthica, Say., found in North America. Many species also occur, mixed with marine remains in the Miocene formations of Touraine, Dax, and Bordeaux, and in the Pleiocene formations of Piedmont, the Crag of England, and its equivalent in Belgium; of these but few are extinct, by far the greater number being referred to existing species. Among the French species described by M. Deshayes is one (//. dubia), which, on the authority of Mr. Underwood, is mentioned as occurring in the Isle of Wight. I have not met with any specimen from that place; and M. Deshayes, as I learn from that gentleman himself, entertaining doubts as to the English locality, I have not considered 7. dudia as an English species. 62 EOCENE MOLLUSCA. No. 14. Het1x Vectiensis. F. #. Hdwards. Tab. X, fig. 8 a—e. H. testa orbiculato-depressd, umbilicatd ; superficie punctulis minutissimis confertis aspersd; spird parum elevatd; anfractibus quinque sub-rotundatis, suturis depressis ; apertura semi-ovalt, peristomate reflexo : umbilico profundo, semi-obtecto. A somewhat convex shell, having the surface thickly covered with minute punctules. The slightly elevated spire is composed of about five bluntly convex whorls, depressed at the sutures. The aperture is semi-ovate, having the margins strongly reflected ; that of the inner lip partly covering the umbilicus, which is deep and moderately wide. The shells, when in the young state, are, like many others in this genus, slightly carinated. In the general contour, this species much resembles the recent H. rufescens, but it is distinguished as well by the punctulated surface, as by the less rounded whorls, the more strongly reflected peristome, and the larger umbilicus. Casts in the Limnzean limestone at Sconce are not uncommon; but specimens with the shell preserved are rare. The casts may be separated from those of H. D Urbani, with which, at first sight, they are liable to be confounded, by the narrower umbilicus, and frequently by the impression of the reflected lip of this species. Where the shell is preserved, the punctulated surface presents a character by which it may be at once distinguished. Diameter, 4-10ths of an inch; elevation, 2-10ths in. Localities—Sconce near Little Yarmouth, and Headon-Hill, Isle of Wight. No. 15. Her1x D’UrsBani. F. 2. Edwards. Tab. X, fig. 5 a—d. H, testa orbiculato-depressd, levi, umbilicatd: spird subprominuld; anfractibus quingue aut sex sub-rotundatis ; suturis perspicuis: aperturd semi-ovali, peristomate simplict ; umbilico magno. A smooth, depressed, umbilicated shell, with a slightly elevated spire; the five or six volutions of which it is composed are bluntly convex, and the upper edges are so much depressed as almost to present a channel at the suture; the aperture is semi- ovate, with a perfectly simple unreflected lip; the umbilicus is wide, disclosing the volutions within. This species somewhat resembles H. Zemani of Brogniart, but the spire is less elevated, and the umbilicus is more open. The smooth and polished surface, which barely shows the lines of growth, and the sharp lip prevent its being confounded with /. Vectiensis. When young, the whorls are slightly carinated. A variety occurs in which the spire is much depressed, and the whorls consequently assume a less bluntly convex form. PULMONATA. 63 The species is not uncommon; but most generally casts only are found. In that condition the wide umbilicus is the only character by which it can be separated from HT. Vectiensis. Diameter, 4-10ths of an inch nearly; elevation rather more than 2-10ths in. Localities —Sconce and Headon-Hill. I have much pleasure in dedicating this species to my friend John D’ Urban, Esq., whose Paleontological pursuits have enabled him to add several interesting species to our Eocene Fauna. No. 16. Hetix Gtosposa. Sowerby. Tab. X, fig. 2 a—d. H. ctoposus. Sow. 1818. Min. Con., vol. ii, p. 157, t. 170. — Morris. 1843. Cat. of Brit. Fos., p. 147. H. testd globoso-conoided, apice obtuso: anfractibus sex aut septem, transversim sub- striatis, ultimo anfractu ad basin convexo; striis numerosis, trregularibus, tenuissimis ; suturis perspicuis ; apertura depressd, semi-lunari, marginibus reflexis ; columella sub-recta; umbilico obtecto. This well known shell is globosely conical, with an obtuse apex; the spire is formed of six or seven whorls, which exhibit obscure, transverse, irregular striee, or lines of growth, so faint that, as Mr. Sowerby remarks, they are only to be seen in the best preserved specimens. The base of the shell is very tumid, rising from the peri- phery of the whorl with a bluntly convex swell until it nearly reaches the umbilicus, into which it sinks abruptly, imparting an almost vertical slope to the columella. The aperture in the adult shell is semilunate and depressed, with the margins reflected, that of the inner lip entirely concealing the umbilicus. The young shell, like that of all the globosely conical shells of this genus, presents a form very different from that of the mature one. When in the young state, the whorls are subcarinated, increase rapidly in size, and consequently are very convex, giving a sub-quadrate form to the aperture ; and the shell presents a small umbilicus: but, as the shell approaches maturity, they lose their sub-carinated form, increase in size more and more slowly, and become less and less convex in their contour, so that, in the mature state, the aperture assumes a semilunate form, and at this period of growth the umbilicus is concealed by the reflected margin. Specimens with the shell preserved are extremely rare, but casts in all stages of growth are comparatively common at Sconce Point. In the young state the casts resemble those of Helix occlusa; but the flattened base, the shorter and more oblique columella, and the semi-ovate aperture, serve to distinguish the latter species. I am indebted to Mr. Sowerby for the use of the original specimen described 64 EOCENE MOLLUSCA. in the ‘ Mineral Conchology,’ from which the larger figures are taken; fig. 2@ is from a specimen in the cabinet of Mr. D’Urban. Diameter, 2 iuches; elevation, 2°3 in. Localities —Shalcome (near Ryde) and Sconce, Isle of Wight. No. 17. Hrtrx occitusa. Ff. #. Edwards. Tab. X, fig. 10 a—e, H. testa sub-globosd, fulvo uni-fasciatd ; spird prominuld, quinquies vel seaies circum- volutd ; anfractibus convexiusculis, ad suturam depressis, obscure ad basin striatis, sub- planulatis ; apertura semi-ovatd, marginibus parum reflexis: margine columellari umbi- licum occludentt. A sub-globose shell, with a somewhat elevated spire, composed of five or six rapidly enlarging convex whorls, depressed round the suture, and flattened on the base. The surface presents numerous, very faint, oblique, irregular striz, produced by the lines of growth. The aperture is of a regular semi-ovate form, having the margins slightly reflected; the inner lip spreads over, and entirely closes the umbilicus. The shell is ornamented by a narrow, brownish-yellow band running round the whorls, just above the line of the suture, the colouring matter of which is retained, more or less, in all the specimens I have seen, in which the shell is preserved. This is a well-marked species, easily distinguishable when the shell is preserved. The casts, which are more commonly found, resemble those of the young shell of H. glohosa, but can be separated from them without difficulty by the flattened base and oblique columella which present a strong contrast with the tumid base, and nearly vertical columella of that species. The smaller number of the whorls and the narrower umbilicus separate it as distinctly from H. Vectiensis and H, D’ Urban. Diameter, 1-2 in.; elevation, # in., nearly. Localities—Sconce and Headon Hill, where it occurs more rarely than any of the preceding species. No. 18. HELIX TROPIFERA. fF. 2. Edwards. Tab. X, fig. 3a—e. /1. testa orbiculari, supra plano-convead, subtis convexo-turgidd, umbilicata : spird plus, minusve elevata ; anfractibus quinque aut sex, ad peripheriam subcompressis, et carinatis ; apertura transversd, subtrigond ; marginibus reflexis umbilico magno. I have seen two specimens only, both casts, of this Helix; from the character of the whorls and the aperture it would belong to Lamarck’s genus Carocolla,—the Chilotrema of Dr. Leach. It is an orbicular shell, with a slightly elevated spire, apparently variable in height; the upper sides of the five or six whorls, of which it is formed, are nearly flat, and somewhat compressed near the periphery, which presents a PULMONATA. 65 sharp keel; the under side is tumidly convex, rising with a regular swell until it approaches the umbilicus, into which it sinks rather suddenly, presenting a blunt angle which defines the umbilicus. In the smaller of the two specimens, the spire is more elevated, and the underside of the body-whorl more convex than in the other. The umbilicus is deep and moderately wide; the aperture transverse, and wider than long. The specimen figured exhibits the impression of a slightly reflected peristome. . The present species is much less than the recent H. /apicida, the umbilicus is smaller in proportion, the keel round the whorls more prominent, and, judging from the cast figured, which appears to be that of a fully-grown shell, the aperture at maturity does not present the downward inflection which characterises 1. lapicida. The condition of the keel is apparently a character of little value, inasmuch as it varies considerably in specimens of //. /apicida, some of which, particularly in the young state, have it as acute and prominent as that of the present shell. The smaller size of the umbilicus, and the absence of the downward inflection of the aperture, are the most important differences; but these characters, even if constant, would scarcely justify my considering the shell as more than a variety. With only two specimens, however, and those casts, I do not venture to pronounce as to their identity with the recent species. If, on more perfect specimens being obtained, it should appear that the shell presents the granulated surface which characterises HT. lapicida, 1 should feel little hesitation in referring it to that species. The specimen figured belongs to Mr. D’Urban’s collection. Size.—Diameter, } an inch; elevation rather more than 2-10ths in. Locality.—Headon Hill, where, however, it is extremely rare. No. 19. HeELix ompHAtus. F. LH. Edwards. Tab. X, fig. 5 a—e. HELIX sTRIATELLA. S. Wood. Lond. Geol. Journ., vol. i, p. 118. H. testa planorbulari, depressd, undato-costulato-lineatd, umbilicatd: anfractibus quaternis, convexiusculis ; suturis conspicuis, depressis: aperturd rotundato-semi-lunari ; marginibus simplicibus ; umbilico magno. This shell, which belongs to the section represented by Zonites, Montfort,* * The genus Zonites, as defined by Mr. Gray, embraces those Helices which have a depressed spire and a lunate mouth, with thin simple lips. It is divided into two sections—Verticillate (Fér.), in which the shell is brown, or varied, and striated; and Hyaline (Fer.), in which the shell is hyaline, greenish or pale brown, and polished. It appears, from the observations of Mr. W. Thompson, to which I have before referred, that, judging from the characters afforded by the dentition, the animal of Z. radiatus (one of the Verticillate) is a true Helix; but that in four species of the Hyaling examined by him, the animals would form a connecting link between Vitrina and the true Helices. Professor E. Forbes and Mr. Hanley, in their ‘History of British Mollusca,’ restrict the genus to the Hyaline species. A) 66 KOCENE MOLLUSCA. (Helicella, Lamarck,) is somewhat discoidal, with a slightly elevated spire formed of about four whorls, generally rounded or bluntly convex, but which, in two casts of fully grown individuals in my cabinet, present a sub-carinated periphery. The surface is covered with numerous regular raised lines, separated by shallow rounded sulci; the limes are oblique, undulating, and rounded. ‘The margins of the depressed semilunar aperture are simple and unreflected. The umbilicus is moderately wide. Mr. S. Wood, in his ‘ List of Shells from Hordwell Freshwater Bed,’ has referred this shell to the North American species, 1. striatella, Anthony; but, although I feel great hesitation in dissenting from his opinion, the differences between the two render it difficult to maintain their identity, at all events, before we are better acquainted with the influence of external conditions in modifying the forms of the animal and its shell. I should add that I have only one specimen with the shell preserved, (the one referred to by Mr. Wood, and which he has been kind enough to add to my collection,) and that this specimen is in an imperfect state. On comparing this shell with the recent H. striatella, it will be seen that in the latter species the spire is more elevated, the lineation sharper, the sulci not so deep, the whorls wider, rounder, and less embracing ; the suture not so depressed, and the aperture larger. Similar differences exist between this and /. ruderata, a species from Cincinnati described by Binney. In ZH. perspectiva, Say, which it somewhat resembles, the spire is more depressed, the lineation, like that of H. striatel/a, is fainter and sharper, the volutions more numerous, the peritreme more distinctly carinated, and the umbilicus wider.* A shell occurs in the Pleistocene freshwater deposit at Clacton, which is referred to H. ruderata: the striation resembles that of the present shell; but in other respects it very closely resembles the American shell. M. Deshayes has described a fossil shell from the upper freshwater formation of the Soissonnais (//. Ferrantii), to which this species presents a general resemblance; but it is separated from that shell by the more elevated spire, and the more numerous whorls ; and in H. Ferrantii the raised lines appear to be fewer and less regular, and the umbilicus to be narrower. Sixe.—Diameter + of an inch, nearly ; elevation 1-10th inch. Localities —Hordwell Cliff ; Sconce. * The H. striatella of Anthony is from Massachusetts, and, until recently, was considered to be merely a variety of Say’s H. perspectiva, which is from Ohio and Lake Erie. Gould, in his ‘Report on the invertebrate Animals of Massachusetts,’ has pointed out the distinctions. The H. ruderata of Binney is from Cincinnati, and has also been considered as a variety of H. perspectiva ; it appears to belong rather to Hi. striatella. PULMONATA. 67 No. 20. HeLIx LAByRINTAICA. Say. Tab. X, fig. 7a—e. Hewrx Lapyrintuica. Say. Journ. Acad. Nat. Se. Philadelphia, vol. 1, p. 124. — — Nicholson's Encycl. (Amer. Edit.), 4. = — Férussac. Hist. Natur. des Moll., tab. lis, fig. 1; Prodromus, No. iil. oe = Binney. Boston Journal Nat. Hist., vol. iii, tab. xxiv, fig. 1. — — Gould’s Report of the Inverteb. of Massachus., p. 184. — wasyrinturcus. S. Wood. Lond. Geol. Journ., vol. i, p. 118. H.. testa minima, globoso-conicd, transversim lineatd, umbilicatd ; lineis obliquis, undosis, numerosis ; spird plus minusve elevatd, sexies circumvolutd ; anfractibus convewis ad basin sub-planulatis : apertura depresso-semilunari, peristomate reflexo : margine columellart uno dente lamelliformi instructo : umbilico magno, profundo. This pretty and very rare Helix is a small, roundedly-conical shell, with a more or less elevated spire, composed of about six gradually increasing whorls, separated by a clearly defined suture, and ornamented with numerous, elevated, obliquely trans- verse, equidistant, raised lines, more or less prominent in different individuals. These lines are somewhat acute, slightly undulated, and, running into the umbilicus, cover the whole surface of the whorls. The base of the shell is but slightly convex; the aperture of a depressed semilunar shape, with the peristome reflected. The columella lip presents a large lamelliform tooth, prolonged within the aperture, and running parallel with the suture. The umbilicus is deep and wide, being about one third of the diameter. In one specimen in my cabinet, the spire is very much depressed, almost planorbular, and the apex more obtuse. This species derives additional interest from the fact that, having survived through the inconceivably long spaces of time required for the deposit of the Miocene and the more recent formations, and having become extinct in the hemisphere in which it first appeared, it is now found among the living forms of North America. The recent //e/ix labyrinthica, first described by Say, is spread over a wide range of country, extending from Ohio to Florida, and from Missouri to Texas. Specimens from Texas, Ohio, and Florida are preserved in the British Museum; and, after a careful comparison with them of the fossil shells, it appears to me that differences of sufficient importance for specific distinction cannot be detected between them; I therefore fully concur with Mr. 8. Wood in the opinion expressed by him of their specific identity, and I do not hesitate to refer the fossil shell to Say’s species. In order to facilitate an examination into this identity, it will be useful to give Say’s description in his own words. It is as follows: ‘Shell conic, dark reddish- brown; body lighter; whorls five or six, with conspicuous, elevated, equidistant, obtuse lines across, forming grooves between them; apex obtuse; lip reflected, 68 EOCENE MOLLUSCA. rounded ; pillar-lip with a large, lamelliform, elongated tooth, which appears to revolve within the shell parallel to the suture; a smaller raised line revolves nearer to the columella within the shell, but becomes obsolete before it arrives at the pillar-lip. Umbilicus large. Breadth 1-10th of an inch.” Taking the Texas shells, the form described by Say as the typical form of the American species, the fossil shell presents, on comparison, the following variations : lst. The shell is somewhat smaller; the spire, except in the specimen I have noticed, is more elevated, the apex not so obtuse, and the whorls are less convex. 2d. The base of the shell is flatter, and the aperture not so rounded. 3d. The position of the larger raised line is more median, and the smaller raised line is wanting; and,— 4th. The peristome is simply reflected, and not “ rounded” or thickened. Now it will be seen that the differences firstly mentioned are such as frequently occur in a series of individuals of the same species. The variable height of the spire, evidenced in the fossil shells by the depressed form of the specimen before mentioned, is a character also found in the recent species; since Gould, in his work above cited, states expressly that “the shell varies considerably in the elevation of the spire, being sometimes much flattened, and again it has a pointed apex;” an observation, the accuracy of which the Florida specimens in the British Museum fully confirm ; and this difference in the elevation of the spire will depend on, and in fact will denote, the less or greater convexity of the whorls. With respect to the flatter base, and the consequently less rounded aperture, the same specimens from Florida exhibit a similar departure from the type; im one instance, indeed, the base is so much flattened as to impart a sub-carinated form to the basal periphery of the whorl. The position of the larger tooth is equally variable in the Texas specimens; and, as regards the absence of the second or smaller raised line, Gould says that, “usually but one of them (7. e. of the raised lines) exists;” a statement, in fact, borne out by some of the specimens from Ohio in the British Museum, in which the second line is not perceptible. It is evident, then, that these variations, occurring as they do in the recent shells, cannot afford sufficient grounds for a specific distinction of the fossil shell; and the only difference which apparently does not elude us on comparison, is the thickened or, as Say describes it, the rounded outer lip of the recent shells. To rest specific distinction on this character, one which, in general, is only an attribute of maturity, and which, even if constant, could, at the utmost, merely serve to designate a variety, would be an excess of refinement. But it cannot be affirmed that this variation is constant, and a larger series of the fossil shells may show that even the thickened outer lip is not wanting. Of the influence of varied conditions in modifying the form of shells, very little is known or even conjectured ; but we may reasonably believe that PULMONATA. 69 a change in the ordinary conditions of temperature, and of the nature and supply of food, will be attended with appreciable differences in the development, although not in the organisation, of the animal; and that these differences will be represented in, and will modify the form of the shell. And to such a cause, perhaps, may be attributable the distinction, trivial as it is, which, as we have seen, exists between the shell of the living H. labyrinthica and those of its Eocene representatives. The identity in question exhibits an instance of a terrestrial species surviving important geological changes, and prolonging its existence through geological epochs of very great extent, but to the probable duration of which no approximation even can be made and yet preserving its normal form almost without modification ; an instance unparalleled, if, as will probably prove to be the case, the various forms of Terebratula referred to the recent 7. caput-serpentis belong to different species. Brogniart, ((Ann. du Muséum d Histoire Naturelle,’ tom. xv, p. 380,) has de- scribed a small trochiform Helix from the neighbourhood of Mans (//. Menard), which, in the general character of its lineation, resembles this species. It is, however, larger ; and the whorls, although described as being “nearly equal,” appear, from the figure given, to enlarge more rapidly. The aperture is neither described nor repre- sented, and it is impossible, therefore, to form any opinion as to the identity of the shell with the present species. Size.—Diameter, 1-10th in.; elevation 1-10th in. Localities.—Hordwell Cliff ; Headon Hill. No. 21. Heurx sus-LaByrintnica. F. 2. Rdwards. Tab. XI, fig. 4 a—e. Hf. testd minimd, globoso-conicd, umbilicatd; spird elevatd, apice obtuso: anfractibus sex, rotundato-convexis, gradatim majoribus, transversim lineatis : aperturd, obliqua, semi- lunari, simplict (2); umbilico parvo. I possess only one specimen, and that merely a cast, of this small and very rare Helix. Although more pupiform than /Z. /abyrinthica, it approaches so nearly to that shell that I feel great hesitation in referring it to a distinct species; on examination, however, differences appear which scarcely justify my describing the shell as merely a variety. It is a small, globosely conical shell, with an obtuse apex, and formed of six roundedly convex whorls, increasing in size very slowly. The impression of the whorls in the matrix presents a faint lineation, too regular to be due to lines of growth merely. The aperture is oblique and semilunar, but is too imperfect to enable me to say whether the peristome was or was not thickened or reflected. On the outer lip of the penultimate whorl are two linear impressions similar to those produced by lamelliform teeth, to the presence of which they may, perhaps, be attributed; but 70 EOCENE MOLLUSCA. they are not continued towards, and do not appear at, the aperture. The columellar lip does not present any evidence of teeth. The umbilicus is rather small. On comparing this shell with 7. /abyrinthica, the distinctions appear to be that, in the present species, the apex is more obtuse, approaching, in that character, more nearly to the recent specimens of that species; the whorls enlarge more slowly, are more roundedly convex, and but slightly, if at all, flattened on the base; the aperture, partaking of the character of the whorls, is rounder, and the teeth, if present, are on the outer lip, and not on the columellar lip, as in H. dabyrinthica ; the umbilicus is smaller, and, if the shell were preserved, would, I think, be nearly closed. Having only seen the single specimen in my collection, I propose the species with hesitation, although the characters seem to me sufficient for specific distinction. Size.—Hlevation 1-10th in. nearly; diameter 1-10th in., nearly. Locality—Headon Hill. No. 22. Hetrx Heaponensis. Ff. /. Hdwards. Tab. XI, fig. 5 a—d. H. testd minutd, orbiculari, sub-depressd, umbilicatd ; spird prominuld ; anfractibus sex, rotundatis, suturis perspicuis : apertura rotundato-semi-lunari, obliqud ; peristomate tncras- sato, refleco ; margine externo tribus lamellis, penitissime decurrentibus, instructo : umbilico lato, profundo. A very small depressedly orbicular shell, with a somewhat elevated spire, com- posed of six or seven rounded whorls, separated by a deep suture; the rounded aperture is oblique, and impinged upon by the body whorl, which gives to it a semi- lunar shape; the peristome is slightly thickened internally, and reflected ; and the outer lip is furnished with three lamelliform teeth, extending far back into the whorls; the umbilicus is wide and deep. The H. Headonensis is apparently extremely rare; my specimen, which I believe to be unique, is merely a cast, and the outward condition of the shell is not shown. The species presents some analogy with the depressed variety of 1. /abyrinthica; but the greater number of the whorls, and the different dentition of the aperture, distinguish it from that shell. In general appearance it resembles the recent H. pulchella ; but the spire is more elevated, the whorls more numerous, and, in the latter species, the aperture is without the plaits which characterise the present shell. The species appears to be well marked and perfectly distinct. Size.-—KHlevation rather more than 1-20th in.; diameter 1-10th in. Locality—Headon Hill. PULMONATA. 71 Genus 7th. Butimus.* Scopoli, 1786. Buummus, Brug., 1792; Lam., 1801. Cocuiba, Adanson, 1757. - CocuLostyLa, Férussac. Gen. Char.—Shell oval, oblong, or turriculated, smooth, or longitudinally striated ; spire obtuse, variable in length and in the number of the whorls, which are generally few, and for the most part sinistral; aperture entire, oval, rounded anteriorly; outer lip simple, generally reflected and confluent with the columella; inner lip reflected over the body whorl; columella smooth. This genus, originally proposed by Scopoli, was adopted by Bruguiére, and extended so as to comprise animals essentially different in their organisation; many genera have, in consequence, been since separated from it by Draparnaud, Lamarck, and others. The animal closely resembles that of Helix ; but M. Deshayes states that it presents a modification of the organs of generation sufficient for generic distinction. The shells may be known from the /Helices by their more elongated spiral form ; from the Limuee by the smooth columella, and from Pupa by the more regularly tapering spire. The genus contains very many living species distributed over the equatorial, tropical, and warm temperate regions, as well of the new, as of the old, world. According to Mr. Lovell Reevet the localities of nearly 600 species have been ascertained; and of these, three fifths inhabit the western hemisphere, principally central America ; and a large proportion, rather more than one third, of the remaining species is found in the Phillippine Islands. Several fossil species, from the Freshwater deposits of the Paris Basin, have been described by MM. Brard, Brogniart, Lamarck, Defrance, Matheron, and Deshayes ; and two distinct species (B. edlipticus, Sow., and B. politus, nov. spec.,) occur in the * The etymology of this word is not ascertained. Adanson in 1757, in his ‘Histoire Naturelle du Sénégal,’ applied the name Bulinus to a species of the shells which afterwards formed part of Drapernaud’s genus Physa, but which have since been separated by Dr. Leach, under the generic name Aplevus ; and the writer of the article “ Limneans,” in the ‘Penny Cyclopedia,’ suggests, and apparently with much proba- bility, that the word Bulimus was used by mistake by Scopoli and Bruguiére for Bulizus. Studer seems to consider Bulimus to have been intentionally substituted for Bulinus, and says that the alteration is altogether inadmissible; and Hartmannn and Mr. Broderip concur in rejecting the name. Herrmansen fancifully derives the word from fovArpos, ingens fames, in allusion, I presume, to the voracity of the animal. The name Bulimus, however, whatever may be its origin or meaning, appears to be generally adopted, and I have therefore retained it. + Mr. Lovell Reeve, “On the Geographical Distribution of the Bulimi,” &c., “Ann. and Mag. of Nat. Hist.,’ 2d ser., vol. vii, p. 241. 72 EOCENE MOLLUSCA. contemporaneous deposits in England. The shell described by Mr. Sowerby (‘Min. Con.,’ vol. iv, p. 89 bis, t. 366), as B. costellatus, is an Achatina. Two of the French Eocene species have been found, mixed with marine remains, in the Faluns of Touraine; but, as yet, no species has been found below the Eocene formations. No. 23. Butimus ELLIPticus. Sowerby. Tab. XI, fig. 2 a—/. Buiimus eviipricus. Sowerby. 1822. Min. Con., vol. iv, p. 46, t, 337. — eNvIstRiaTus. G. Sowerby, jun., 1846. Lond. Geol. Journal, vol. i, p. 20. B. testa sinistrorsd, ovali, elongata ; apice obtuso: anfractibus plano-convexis, superné sub-canaliculatis; transversim lineatis; lineis obliquis, irregularibus, plus minus-ve numerosis ; apertura sub-auriformi, peristomate simplici, margine columellari reflexo. A sinistral, cylindrically-conical shell, with an apex more or less obtuse in different individuals ; the whorls are slightly convex, depressed at the upper margin so as to form an obscure channel running parallel with the suture, and covered with numerous transverse raised lines, which are rounded, oblique, and vary considerably in number, frequently in the same specimen. ‘The aperture is oblong and ovate; the sharp outer margin is slightly reflected where it joms the columella, and is frequently thickened as it spreads over the body-whorl. Fig. 2f is taken from a specimen belonging to Mr. Wetherell, found in the exca- vations in the London Clay at Primrose Hill for the London and Birmingham Railway. The lineation of this fragment is fainter and more crowded, and the whorls appear to be more angular at the base than in BZ. el/ipticus; these distinctions mduced Mr. G. Sowerby to refer the shell to a distinct species. The faintness of the transverse lines is, however, due to the worn state of the shell, which has apparently lost the outer layer; and their number is a character too uncertain to be relied upon. The specimen represented by fig. 2a, from Mr. D’Urban’s collection, shows on one side of the penultimate whorl, lines nearly as crowded as those on the Highgate specimen, while those on the opposite side of the same whorl are moderately distant; and I have in my own collection a specimen, beautifully preserved, in which the same discrepancy occurs. The angularity of the whorls is a character frequently found in shells in an early stage of their growth, and I have several young shells of this species, in which the whorls present a clearly defined angle running round the basal periphery. On these grounds I have referred the specimen in question to the present species. A form occurs at Binsted, near Ryde, in which the whorls are flatter than in ordinary specimens, and sub-turrited; in other respects it agrees with this shell, of which, therefore, I consider it to be only a variety. PULMONATA. 73 Size-—The specimens ordinarily found rarely exceed 25 inches in length by 9-10ths of an inch in diameter; one specimen, however, in my collection is above 3 inches long, and rather more than 1 inch and 2-10ths in diameter; and the shell from which fig. 2¢ is taken, forming part of the valuable collection of the late Mr. Dixon now in the British Museum, must have exceeded even those dimensions. Localities. —Shalcombe, Binstead, Sconce, in the Isle of Wight. No. 24. BULIMUS POLITUS. : . Tab. XI, fig. 1 a—d. B. testa conicd, levissima, polita ; apice decidue ; anfractibus sub-conveais ; apertura ob-ovali, anticé effusd, postice sub-angulatd, peristomate incrassato, reflexo. The occurrence of this shell in the fuvio-marine deposit in Headon Hill in such abundance as almost to be inconsistent with the supposition that it is a land shell, suggests that it might be placed with those Paludinz, in which the margins of the aperture are thickened or reflected, and of which an instance (Paludina Chastellii, Nyst,) occurs in a similar formation in Hampstead Cliff. The aperture, however, and the smoothness of the surface, place it, perhaps, more correctly in the present genus, although the latter character is frequently shown in well-preserved specimens of Paludina found in a somewhat similar matrix. The shell is conical, with a smooth polished surface, on which faint lines of growth are barely perceptible; the apex is subject to decollation, leaving about four convex whorls ; the last of which, somewhat like that of Nematura, is slightly contracted near the aperture, which is rounded and very effuse in front, and angulated behind; the peristome is thickened and reflected. The length of the aperture is about 2-5ths of that of the whole shell. The specific name is one by which the shell is generally known. I do not know by whom it was imposed, but it well describes the smooth and polished appearance of the shell, and I have therefore retained it. Size.—Elevation 2-10ths of an inch; Diameter 1-10th in. Locality—Headon Hill. Genus 8th. AcHATINA.* Lamarck. Cocuuttoma, Férussac. Gen. Char.—Shell oval or oblong, subturreted, with an elevated spire; generally smooth, but sometimes longitudinally striated: aperture oval or pyriform, generally greater in length than in width; outer lip thin, never thickened or reflected ; columella * Etym., Diminutive of Aya@os, beautiful; or of Ayarns, an agate. 10 74 EOCENE MOLLUSCA. smooth, inflected and truncated at its base, forming a slight notch where it joins the outer lip. The third division made by Bruguiere in his genus Bulimus, consisting of those species in which the columella is truncated at the base, was formed by Lamarck into the present genus. From this Montfort withdrew his genera Liguus, (Chersina, Humph.,) consisting of the conical forms in which the aperture is short and nearly round; and Polyphemus, comprising the oblong sub-turreted species, with an un- dulating outer lip, to which Bolten had already given the name Oleacina, and which forms the genus Glandina of Schumacher and Say, and the sub-genus Cochlicopa of Feérussac. As some of the Bulimi present a sharp outer lip, the truncation of the columella appears to be the only character by which the Achatinz can be separated from that genus, and the value of this character must depend on its being the result of some peculiarity of generic importance in the organisation of the animal. M. De Blainville states that he has observed in the animal of Achatina zebra an interruption in the collar where the two sides unite, as if caused by the exsertion (saillie) of the columellar muscle, and to this he attributes the truncation of the columella; but, according to Ferussac, this truncation is not the result of any peculiar organisation, as is the case in other molluscous animals, the columella of whose shells present this character; and that author therefore unites the Achatine to his genus Helix, of which they form the sub-genus Cochlitoma; and M. Deshayes, on account of the similarity of organisation presented by the animals of Bulimus and Achatina, proposes to re-unite Achatina with Bulimus. The genus, however, is very generally adopted as well by English as by foreign Malacologists, and I have therefore retained it. The subdivisions proposed by Bolten and Montfort depend on the proportions and other characters in the shell, of trifling importance, which are generally considered as insufficient for generic distinction, however useful they may be for the division of a genus into sections. The recent species 4. glans, and the cognate species which form the genus G/andina, are confined to the West Indian Islands, and the adjacent parts of the American Continent; and the peculiar form of the outer lip may be used with convenience, as one of the indications of the limits of geographical dis- tribution of species. The Achatinz are generally large shells; some, in fact, attain a greater size than any other land shells at present known, and many are covered with an epidermis. Although generally dextral, they are in some species constantly sinistral. They are found chiefly in tropical climates, and, according to Blainville,in marshy lands. Some few are European, but only one or two small species occur in England. One fossil species (4. pellucida) has been described by M. Deshayes from Parnes; and Bouillett, in his catalogue of the fossil shells of Auvergne, has given another species, which he refers to the recent 4. acicula (Lamarck). — t PULMONATA. No. 25. ACHATINA COSTELLATA. Sowerby. Tab. XII, fig. 1 a—/. BuLIMUs cosTELLATUS. Sow. Min. Con., vol. iv, p. 89 bis, t. 336. Limnea Maxima. Sow. Ib., vol. vi, p. 53, t. 528, fig. 1. Butts costevLatus. Morris. Cat. of Brit. Foss., p. 140. Limn2us Maximus. Morris. Ib., p. 148. A. testa ovato-oblongd, apice sub-acuto ; anfractibus sex convexiusculis, longitudinaliter costellatis, ad suturam adpressis et irregulariter sub-crenulatis ; costellis parum obliquas, irregularibus: aperturd pyriformi, dimidium totius teste in longitudinem Jeré equant, margine externo undato. Var. ABBREVIATA. Fig. 1i—kh. A. testa ventricosiori, breviort ; anfractibus quinque, convexioribus ; apertura longiort, spiram in longitudinem superantt. Shell oval-oblong, with a somewhat acute apex; the six volutions, of which the spire is formed, are more or less convex in different individuals, and are longitudinally ribbed; the edges are slightly pressed against the preceding volution, so as to present a narrow band running round the spire, parallel with the suture; the ribs are rounded, irregular, rather oblique, and slightly thickened above the sutural band, giving a rough crenulated appearance to the edges of the volutions; they are crossed, saltierwise, by very faint obscure lines of growth, perceptible only in well-preserved specimens. ‘The aperture is pear-shaped, and about half as long as the entire shell; the outer lip undulated. The truncation of the columella, a character which the imperfect state of the specimens figured by Mr. Sowerby did not enable him to detect, places the shells, described by that author as Zimnea maxima and Bulimus costellatus, in the present genus. The volutions are variable, being in some specimens less convex than in others ; and the aperture in the young state is comparatively longer than that of the mature shell. A similar change in the relative proportions of the spire and the aperture at different stages of growth is not of infrequent occurrence, and is exhibited in some of the recent species in this genus, particularly in Achat. striata, (Glandina truncata, Pfeiffer.) These considerations, confirmed by the examination of along series of shells of the present species in different stages of growth, have induced me to consider Lu. costellatus as merely the young form of the shell figured as Limnea maxima. ‘The more regularly conical form of the spire, the only distinction by which the former is separable from the latter, is mainly due to the preservation of the shell in the specimen figured, and is a character which cannot be relied upon. The present species belongs to the group constituting the genus G/andina, and is another instance of the approximation of an European Eocene land Mollusc to the living forms of the Western world. Size.—Axis 2} inches, nearly ; diameter 9-10ths of an inch. The specimen represented by figs. 17 and 14, resembles the type in the crenulated 76 EOCENE MOLLUSCA. edges, and costellation of the volutions, in the shape of the aperture, and in the character of the columella; and I consider it, therefore, as merely a variety. It is a ventricose shell, with a shorter spire, and more convex whorls; the aperture is longer in proportion, exceeding the spire in length, owing probably to the shell not having attained maturity. The specimen, the only one I have seen, belongs to Mr. D’Urban’s collection. Size.—Axis 1 inch and 6-10ths; diameter, | inch, nearly. Localities.—Sconce, Shalcombe, Binstead, Isle of Wight. Genus 9th. Pupa.* Lamarck. 1801. CocuLoponta, (sp.), Férussac. CocHLopina, (sp.), Férussac. CocHLoGENA, (sp.), Férussac. Gen. Char.—Shell cylindrical, elongated, or sub-globose ; apex generally obtuse, sometimes acuminated ; whorls numerous, slowly increasing, the last smaller than the penultimate one; frequently striated or ribbed; aperture generally elliptical, some- times sub-quadrate in front, and rounded behind; peritreme continuous, slightly incrassated and reflected; outer lip dentated; teeth variable in number; one or two plaits on the columella. The present genus is one of the dismemberments effected by Lamarck of Bruguiére’s genus Helix. The organisation of the animal bears a strong general resemblance to that of the animals of Helix and Bulimus; and Ferussac has reunited the genus to Helix, in which it is distributed among the sub-genera Cochlodonta, Cochlodina, and Cochlogena. The shell, however, prevents striking dissimilarities, and in the animal, according to M. Deshayes, the same modifications of the generative organs occur which distinguish the animal of Bu/imus. The elongated cylindrical form of the spire, the proportion of the last whorl to the penultimate one, and the direction of the aperture which is parallel with the axis, distinguish the shell from /He/ixv ; and it is separated from Lwlimus by the numerous and slowly increasing volutions, and by the teeth and folds with which the outer lip and the columella are furnished. It is to Clausilia that it bears the closest resemblance ; but from that genus it is separated as well by the aperture as by the absence of the clausium, a character which, however, can seldom be available to the Paleeontologist. In the animals of several of the smaller species the peduncles only exist, the ten- tacles becoming obsolete. Some of these species are sinistral and hyaline, and form Miiller’s genus Vertigo. The animal, however, exactly resembles Pupa in everything but the absence of the tentacles, and, inasmuch as their disappearance is very gradual * Etym., from a supposed resemblance to the Pupa or Chrysalis of some insects. PULMONATA. 77 in the smaller species, M. Deshayes attributes but trifling value to that character, and proposes to suppress the genus altogether. The living species are very numerous and widely disseminated, but the larger ones are confined apparently to tropical climates. The fossil species are few; one species (Pupa Defrancii) is described by Brogniart from the Freshwater deposits of the Paris basin. Bouillet, in his catalogue of the fossil shells of Auvergne, gives two others referred to recent species; and Matheron describes two more species from the South of France, one from the Fresh- water formation at Baux, and the other from the middle beds of the lignite formation near Rognac. No. 26. Pupa PERDENTATA. Ff. HL. Hdwards. Tab. XI, fig. 7 a—e. P. testa cylindrica ; apice . . ? anfractibus planulatis, longitudinaliter costellatis, ad basin sub-angulatis ; costellis aculis, numerosis, irregularibus, undulosis, parum obliquis ; apertura sub-quadratd, multis lamellis inequalibus, penitissimé decurrentibus, utroque margine enstructa. The imperfect state of my specimens, which are merely casts, will not enable me to do much more than to record the existence of this well-marked species. The dentition they present rather belongs to Clausilia than to Pupa; but as this is a dextral shell, and all the known Clausilie are sinistral, I refer it to the present genus. I possess Six or seven specimens only, all without the apex, and the largest showing only the last three whorls. The characters, so far as they can be given from these fragments, are as follows :—Shell cylindrical, apparently elongated, and composed of many whorls; the whorls nearly straight, longitudinally costellated, and bluntly angulated at the base; the costellz sharp, oblique, numerous, irregular, undulating, and separated by deep rounded sulci, and here and there one of them terminates abruptly, bemg cut short by the confluence of the sulci. The aperture, owing to the angular base of the body-whorl, assumes a subquadrate, or rather a lozenge shape ; the outer lip presents no less than fourteen lamelliform teeth, six of which are large, having smaller teeth between them; the columellar lip is armed with three large Jamelliform teeth, and four smaller. These teeth are not merely marginal, as is usually the case in this genus, but are continued, like those of Clausilia, far back into the whorls. Size—Axis . . ? diameter, 2-10ths of an inch nearly. Locality.—Sconce, where it is very rare. 78 EOCENE MOLLUSCA. No. 27. Pupa oryza. JF. 2. Edwards. Tab. XIV, fig. 3a—d. P. testa pared, ovato-cylindraced, ad utramque extremitatem equalter attenuata ; apice sub-obtuso; anfractibus octonis, convewiusculis, longitudinaliter tenuissime costellatis ; suturis profundis ; apertura ovato-oblongd, angustd, obliqua, quaternis dentibus magnis tnstructa. A small cylindrical oval shell, tapering equally towards both extremities ; the apex is rather blunt; the whorls, which are eight in number, are slightly convex, separated by a deep conspicuous suture, and transversely costellated ; the costellz are numerous, very slender, and oblique. The aperture is ovate-oblong, narrow, and somewhat oblique; the outer lip is furnished with four prominent lamelliform teeth, of which the two anterior are the longest. I possess only one specimen, a cast, of this species; and the state of the aperture does not enable me to say whether the columellar lip is furnished with teeth. The species appears to be perfectly distinct. Size.— Axis 2 lines; diameter 1 line. Locality—Headon Hill. Genus 10th. Cuausiu1a.* Draparnaud. 1805. Gen. Chav.—Shell sinistral, cylindrical, elongated, consisting of numerous volutions, generally transversely striated; rather blunt at the apex, and enlarged towards the middle; aperture irregular, oval; peristome continuous, free, reflected, with several columellar and other tooth-like plaits, and furnished with an appendage, termed the clausium, attached to the columella, by which the aperture is partially closed when the animal is withdrawn into the shell. The clausium, from which the present genus derives its name, answers the purpose of an operculum, with which, however, it presents no further analogy than that it serves to enclose and protect the animal within the shell. It consists of a narrow, flat, and very thin calcareous pedicle attached by the posterior extremity to the columella, and expanding at the opposite end into a linguiform plate, which nearly closes the aperture of the penultimate whorl, a small canal across the anterior part of the aperture being left uncovered, probably for the purpose of respiration. In some species when the outer lip presents teeth, the clausium is notched for their reception. This curious appendage is formed when the animal approaches maturity, probably at the same time with the projected reflected mouth. The pedicle is very flexible, and yields to the * Etym. Clausium, (quasi clausus, closed, or claustrum, a door,) the appendage by means of which the animal is enclosed in the shell. PULMONATA. 79 slightest pressure, as the animal emerges from the shell, and the clausium is then bent back against, and fits upon, the curved columella, but recovers its former position by the recoil of the pedicle on the removal of the pressure when the animal withdraws itself into the shell. This peculiar appendage was described first by D’Aubenton, and subsequently by Miiller; and the group of shells characterised by its presence was formed by Draparnaud into the present genus.* The animal of Clausila, so far as its organisation is known, resembles that of Pupa, but Lamarck considered that the differences in the form and condition of the aperture to which I have already referred, were in themselves sufficient for generic distinction without reference to the presence of the clausium. On the other hand, Férussac has placed Clausilia in his genus Heliz, where it forms part of his sub-genus Coch/odina ; and M. Deshayes has been induced, by the resemblance between the external characters of the animals, by the similarity of their habits, and by the gradual passage from the one genus to the other by intermediate species, to propose the union of the two genera. Unless, however, peculiarity of structure or form in the shell is to be altogether disregarded, the presence of so singular an appendage as the C/ausium must surely be considered as sufficient ground for the separation of this genus. Nearly two hundred living species, mostly small shells, are known; several are found in this country, but they occur in great profusion in Southern Europe ; the larger species belong to tropical climates. Only three fossil species I believe have as yet been described; viz., C. antiqua, from the Freshwater limestone of Ulm; C. maxima, from the neighbourhood of Dax, and C. campanica, from the Freshwater limestone of Provins, in which the Paleotherian remains occur. No. 28. CLAuSsILIa STRIATULA. F. £. Edwards. Tab. XI, fig. 6 a—A. Cl. testa subturritd, cylindracea, ad utramque extremitatem attenuatd, transversim lineata : anfractibus numerosis, plano-convewis, ultimo ad basin porrecto ; apertura ovato- pyriformi, obliqua ; peristomate soluto, parum reflexo : lamellis quinque, duobus margine externo, tribus margine columellari, instructo. A: cylindrical, subturreted shell, attenuated at each extremity ; the whorls are very slightly convex, and covered with numerous rather oblique raised lines, separated by broad rounded sulci, occasionally confluent ; the last whorl detaches itself, and projects obliquely forward, terminating in an ovate, pyriform aperture, the margins of which are free, and a little reflected. The outer lip presents two unequal plait-like teeth, the smaller one near the middle, the larger one near the posterior angle of the * A particular account of the Clausium has been given by Mr. Miller, in the ‘Annals of Philosophy,’ vol. i, p. 378; and by Mr. J. E. Gray, in the ‘Zoological Journal,’ vol. i, p. 212. 80 EOCENE MOLLUSCA. aperture. On the columellar lip are three similar teeth, one, very large, close to the columella. I have not been so fortunate as to meet with any specimen having more than fragments of the shell preserved; the description therefore is principally taken from casts. The chief characters presented by them, namely, the large pliciform teeth and the produced aperture, are, however, plainly shown. The specimen represented by figs. 6@ and 6 4 is, I apprehend, the young shell. Size-—My most perfect specimen of the mature shell bas apparently lost the upper six or seven whorls; in its present state it presents six whorls only. The length of the axis is 6-10ths of an inch, nearly; the diameter 2-10ths, nearly. In a perfect state it was probably nearly an inch long. Locality— Sconce, where it is very rare. Genus 11th. SuccinEA.* Draparnaud. 1801. AmpuiBuLiMa, Lamarck, 1805; Hartm., 1821. AmPHIBULIMUS, Montf., 1810. CocutLouypRA, Férus., 1819. Gen. Char.—Shell ovate, or ovately conical, rather elongate; volutions few; spire short, pointed ; aperture large, entire, longitudinally ovate, oblique ; peristome sharp, not thickened nor reflected, and confluent with the columella; inner lip spread over a part of the body whorl; columella smooth, sharp-edged, with an imperforated axis. This genus, first created by Draparnaud, has been received without question by all Malacologists except Férussac, with whom it forms the sub-genus Cochlohydra in his extensive genus Heliz. The animals, like all others of this family, present a strong general resemblance to the typical Helix ; but, according to M. Deshayes, they offer modifications of the generative organs, which differ alike from those of Heliz and of Bulimus. WUamarck, in ignorance of Draparnaud’s genus, proposed his genus 4m- phibulima, which he afterwards suppressed, adopting the name given by Draparnaud. The shells are distinguished from @ulimus by the thin outer lip, and the rapidly enlarging whorls; and from Limn@a, to which they more nearly approach in general form, by the columella, which is thin, smooth, and sharp, and destitute of the oblique fold which characterises the columella of the latter genus. The Succinee are strictly land animals; for, although frequently covered by water and capable of long submersion, they live habitually on land in damp marshy places, near the margins of pools or ditches. The living species are not numerous, and are found chiefly in temperate climates. * Etym., Succineus, of amber, 7. e., amber-coloured. PULMONATA, 81 The fossil species are very few. Two only have hitherto been described ; both from the Pleiocene formations, and both referred to living forms, viz., S. putris and S. oblonga, from the Mammaliferous Crag, (Wood’s ‘ Crag. Moll.,’ p. 5). The latter species is also given by M. Nyst, (Coq. Foss. de Belg.,’ p. 446,) as occurring in the corresponding formation in Belgium. No. 29. SuccrneA rmpERspicua. SS. Wood. Tab. XI, fig. 3a—d. S. mrerspicua, S. Wood. 1847. Lond. Geol. Jour., vol.i, p. 118. S. testd ovatd, ventricosd, tenui, levi; spird brevissimd, obtusa : anfractibus tribus, convexis, ad suturam sub-depressis: apertura rotundato-ovatd, sub-verticali, bessem totius teste in longitudinem superanti. This exceedingly rare shell is thin, smooth, ovate, and composed of three ventricose volutions, rather depressed at the suture. The spire is very short and obtuse ; the aperture large, nearly vertical, and in length fully equal to two thirds of the whole shell. I have three specimens only of this shell: two from Hordwell, for which I am indebted to Mr. S. Wood; the third is from Headon Hill. Size.—Axis rather more than 2-10ths of an inch; diameter, 3-10ths of an inch. Section PB. Aguatica, Fleming. Limnopuita, Hartm. HyeGropuita, Féruss. Family—LiMn 21D 2. Genus 12th. Limnama.* Zamarch. Buccrinvn, (sp.,) Miiller, 1774. Buiimvs, (sp.,) Scopoli, 1777 ; Bruguiére, 1792. Lymnea, Lamarck, 1801; Risso, 1826; Valenc., 1833. Limnevs, Draparnaud, 1805; Brogniart, 1810. Lymnevs, Brard, 1809; D’Ord., 1841. Lymnus, Montfort, 1810. Loin, De Férussac, 1821; Nillson, 1822; Grateloup, 1838; Bronn, 1838. Limnavus, Oken, 1815; Rossmasler, 1835; Turton, 1831. Staenicoia, Leach, 1820. Guinaria, Leach, 1820. * Etym., Acuvaios, belonging to, or growing in, pools or marshes. lt 82 EOCENE MOLLUSCA. Lymyma, J. Sowerby, 1818; De Blainville, 1825; Desmarest. Limnga, G. Sowerby, 1822; Fleming, 1828; G. Sowerby, Jun., 1840. — Swainson, 1837. LEPTOLIMNEA, Swainson, 1840. Lymnopuysa, Fitzinger, 1833. LymnuLa, Rafinesque, 1819. Gen. Char.—Shell ovate or elongated, frequently turreted, generally thin, smooth ; spire always apparent, more or less elevated: volutions convex, somewhat depressed, sometimes ventricose, and rapidly enlarging; aperture large, entire, longitudinal, ovate, with a tortuous columella bearing an oblique fold; peristome sharp edged. The shells forming this genus, constituted part of the genus Bu/imus of Scopoli and of Bruguiére ; they had previously been separated by Miiller from the other land and freshwater Molluscs under the generic name Buccinum, applied to them by Lister and Geoffroy. In lieu of this name, which has been applied by Linnzus to a group of marine branchiate Molluscs, Lamarck substituted that of Zymuea, etymologically Limnzea. The animal carries on its head two compressed triangular tentacles, enlarged at their bases, at the inner and anterior parts of which the eyes are placed. Like most others of this order, the Zimnee are hermaphrodite, and although the union of two individuals is necessary for fecundation, as among the Helicide, yet impregnation is not mutual, as in that group; but the same animal performs the male and female functions successively with different individuals. The genus, as at present defined, is composed exclusively of the thick dextral shells, with a fold on the columella, in which the inner lip is not extended over the body whorl; the genus Amphipeplea, (Nillson, the MS. genus Myzras of Dr. Leach,) having been proposed for the dextral forms with a plaited columella, in which the shell is thin and polished, and the inner lip expanded. The sinistral forms, without the columellar fold, have been separated under the generic names Physa (Draparnaud), and Aplerus (Fleming), the Bu/inus of Adanson. The propriety of these subdivisions is questioned by Mr. G. Sowerby in his ‘ Genera of Shells ;’ but, besides the conchological differences above mentioned, there are zoological distinctions which are generally admitted as sufficient grounds for retaining them. These are, in Physa and Amphipeplea, the condition of the mantle, the edge of which is lobed and capable of extension, so as to cover the shell, which thence acquires the polished and shining surface characteristic of those genera; and the form of the tentacles, which are elongated and filiform, and not thick and triangular, as in the present genus. In Aplerus the edge of the mantle is, as in Limnea, simple and not extendible over the shell; that genus, therefore, bears the same relation to Physa which Limnea bears to Amphipeplea.* * The propriety of these divisions is, to some extent, confirmed by the observations of Mr. W. Thompson, to which I have before referred. That author, speaking of the dentition in the different genera of the Pulmonata, states that “the character of Limneus appears to be to have one small central tubercle, as it were, PULMONATA. 83 The Limneee are inhabitants of freshwater streams and pools, and occasionally of brackish marshes. The living species are found in all parts of the world, but principally in the temperate zones. In the fossil state, species have been found in the Wealden formations; and they occur in great profusion in the freshwater deposits of the Eocene epoch, and, in greater or less abundance, in nearly all the lacustrine formations above those deposits. In England, as in the Paris basin, the fossil Limneez occur in very different conditions in the various deposits; in the limestone of the lower formation, called, from the abundance of their remains, the ‘‘ Limnzean Lime- stone,” specimens with the shell preserved are very rare ; generally only the casts are found, the shelly matter having been absorbed. In the upper marls they occur in great profusion, and, although very fragile, usually in a beautiful state of pre- servation. It is exceedingly difficult, as both Lamarck and De Blainville have observed, to distinguish the different species ; the length of the spire, the contour of the volutions, and the size and shape of the aperture, characters by which species may be separated with tolerable certainty, in other genera, are, in this genus, exceedingly variable, and glide by imperceptible gradations from one extreme to another; so that reliance cannot be implicitly placed on them. The character which appears to exhibit the least variation is the columellar fold, although this also occasionally presents con- siderable differences in form and condition. By this character, however, the genus may be divided into two groups, one comprising the species in which the fold is flattened ; the other consisting of the species in which it is rounded or sub-acute. Each of these groups may, again, be subdivided into two sections, according as the upper parts of the whorls, forming the sides of the spire, are convex or flat. By the use of these artificial distinctions, the separation of the species will be much facilitated. Sect. a. Columellar fold compressed, generally bipartite. No. 30. Limnzwa caupata. Ff. £. Hdwards. Tab. XII, fig. 2 a—e. L. testé ovato-acutd, ventricosd, levi: anfractibus numerosis, convexiusculis, ultimo penultimoque rapide crescentibus : ultimo obsoleté et irregulariter corrugato: spird conico- « squeezed up’ between two very large lateral ones, each primary lateral having a very large apex internally, with a small external one, while, at the edge, they have altered to one thick prolonged apex projecting inwards, and irregularly lobed on its upper edge. Much the same arrangement prevails in Amphipeplea, where, however, the tubercle of the lateral teeth is even still larger in proportion toits plate. Physa, again, exhibits a multitude of teeth of a similar form, though different to any that I have seen in other genera.” The dentition of Aplexus is not described. 84 EOCENE MOLLUSCA. subulatd : aperturd magna, in medio dilatatd, anticé coarctatd, spiram in longitudinem superanti: plicd columellari compressa, proeminenti, valde obliquatd, obscure sulcata. Var. ABBREVIATA; testd anfractibus septem vel octo; spird breviori; aperturd longiort. Shell ovate-acute, ventricose, smooth, composed of eight or nine convex volutions, of which the first five or six increase slowly, and the last enlarge rapidly; so that the spire assumes a conical awl-like shape, while the body-whorl is very ventricose. The last two volutions frequently present concentric, obscure, irregular corrugations, giving a crumpled appearance to the shell, similar to that which distinguishes the recent L. stagnalis. The aperture is large, effuse towards the middle, but contracted at the anterior part, and somewhat larger than the spire. The columellar fold is flat, prominent, rather strongly twisted, and generally obscurely sulcated. A variety occurs (fig. 2c) in which the shell is more ventricose, the whorls fewer, the spire shorter, and the aperture proportionally larger, equalling two thirds of the whole shell. The Z. cavdata, in its general appearance and awl-like spire, much resembles L. stagnalis ; but, in the latter species, the whorls are more convex, the body-whorl more ventricose, the posterior part of the aperture more effuse, and the columellar fold is rounded, smaller, and more oblique. Individuals occasionally occur which, from the small degree of convexity in the whorls would, at the first glance, be referred to L. fusiformis; but they may be easily separated by the columellar fold, which, in the latter species, is rounded, and presents a more graceful spiral than that of LI. caudata. Size.-—Axis 24 inch, nearly ; diameter 1 inch. Localities —Hordwell Cliff and Headon Hill. No. 31. LIMNHA PYRAMIDALIS. Desh. Tab. XIII, figs. 2a—, and 3 a—4. LYMN©HA PYRAMIDALIS. Desh. 1824—37. Desc. des coq. foss., &c., vol. ii, p. 95, t. 20, figs. 14, 15. LIMNEA 5 J. Sow. 1825. Min. Con., vol. vi, p. 54, t. 528, fig. 3. LIMN®A 33 Bouwill. 1836. Catal., des coq. foss. de Auvergne, p. 124. LyMNEE PYRAMIDALE? Brard. 1810. Ann. du Mus., vol. xv, p. 407, t. 24, fig. 2. LyMNEUs PyRAMIDALIS? Fér. 1814. Mém. geol., &., p. 60, No. 3. L. testé ovato-acutd, ventricosd, levi; anfractibus septem vel octo convexis: apertura magna, antice dilatatd, spiram in longitudinem superanti ; labio parum expanso ; columella marginatda ; plicd columellart magna, compressa, obliqua, in medio sub-bipartita. A smooth, ovate-acute, ventricose shell, composed of seven or eight convex whorls, separated by a simple, well-defined, but not deep suture: the aperture, which is fully as long as the spire, is large and effuse ; the inner lip but slightly spread over the body-whorl, and the columella presents a margin formed by the thickened inner lip, and bears a prominent oblique fold, obscurely sulcated. PULMONATA. 85 The whorls enlarge more regularly in this species than in Z. cawdata, and the shell, consequently, is more pyramidal in its general form; and the columellar fold is not so prominent nor so much twisted as in that species. From L. /us/formis it is distinguished by the greater convexity of the whorls, and the flattened sulcated fold. The rounder whorls, the depression of the upper margin, and the acute fold of Z. ciucfa, separate it, as clearly, from that species. Although M. Deshayes, in his description of Z. pyramidalis, cites Brard without comment, I feel great difficulty in referring his shell to Brard’s Z. pyramidalis. That shell, judging from the description and figure, is elongated and narrow, and corresponds, as well in the contour and proportion of the whorls and the form of the aperture, as in the character of the depressed columellar fold, with LZ. longiscata, to which species I think it belongs. It certainly appears to differ widely from the ventricose and comparatively short shell described by M. Deshayes, in which the aperture is large and effuse, and the fold prominent.* The English specimens referred to L. pyramidalis of M. Deshayes, agree very well with that author’s description and figure, but not with Brard’s; while, on the other hand, adult specimens of ZL. longiscata frequently occur, which correspond with Brard’s LZ. pyramedalis. The shell represented by fig. 3a—@, for the use of which I am indebted to Mr. Sowerby, is narrower than the type of this species ; and the volutions are so flat, and the general shape so fusiform, that, at first sight, it might be referred to L. fusi- formis. The fold, however, is flattened and sulcated; and I therefore consider it to be merely an aberrant form of L. pyramidalis, combining the columellar fold of that species with the flat-sided spire and subfusiform shape of L. fusi/ormis. Size.—Axis 2 inches; diameter, 9-10ths of an inch, nearly. Localities —Hordwell; Headon Hill; and in France, La Villette, Montmartre , and Vergnols, near Aurillac. No. 32. Limnma toneiscaTa. Brard. Tab. XII, fig. 3 a—t. Lymnfe erriciz. Brard. 1809. Ann. du Mus, vol. xiv, p. 432, t. 27, figs. 15, 16. — PYRAMIDALE, Brard(?) 1810. Ib., vol. xv, p. 407, t. 24, fig. 2. LIMNEUS LONGIscatuS, Brogn. 1810. Ib., p. 372, t. 22, fig. 9. — — Brogn. 1811. Jour. de Phys., &., vol. 72, p. 421. LyMNEUS Lonetscatus, Fér. 1814. Mem geol., &., p. 59, No. 1. LimneEa LonetscatTa, Sow. 1823. Min. Con., vol. iv, p. 57, t. 343. LyMN zA — Desh. 1824. Desc. des coq. foss., &c., vol. ii, p. 92, t. 11, figs. 3, 4. — — Desh. 1824. Encycl. Meth. Vers., t. 2, p. 356, No. 1. * This want of resemblance between the L. pyramidalis of M. Deshayes and that of Brard is noticed by Bouillet in his Catalogue above referred to. 86 KOCENE MOLLUSCA. Linea LoneiscaTa, Lyell and Murch, 1829. Mém. sur les dépots lacustres tert. du Cantal. LIMN®A — Bouill. 1836. Cat. des coq. foss., &c., p. 157, No. 6. = — Gratel. 1838. Cat. des débris foss., &c., du Bassin de la Gironde, p- 33, No. 100. LyMNZA — Desh. 1838. Lam. Hist. Nat. &., 2d edit., vol. viii, p. 422, No. 7. L. testa levi, elongata, sub-turritd, acuminata: anfractibus sex aut septem, convexius- culis ; suturis sub-depressis : apertura ovato-acutd, antice dilatatd, spiram in longitudinem vie equanti ; labro parum expanso ; columelld marginatd ; plied columellari lata, compressa, parum eninenti, bipartita. Var. pistorta; testd longiort, angustiori, anfractibus plus decurrentibus ; apertura breviort. This Limnzea is more abundant, and, although it presents many varieties of form, is, perhaps, better characterised than any other fossil species. It is a smooth, elongated, narrow, subturrited shell, composed of seven or eight convex whorls, somewhat depressed at the suture. The aperture is oyal, rather effuse in front, and, in the typical form, is a little shorter than the spire; the inner lip is thick, but does not extend much beyond the aperture. The columellar fold is broad, flat, not very prominent, and widely but not deeply sulcated. A variety frequently occurs (fig. 3 e—A), in which the line of the suture runs below the wide part of the whorl, giving an irregular distorted appearance to the shell, and shortening the aperture, the length of which barely equals two fifths of the whole shell. Although there can be but little doubt that this is the true Lymnée efilée of Brard, the columellar fold does not correspond with the description given by M. Deshayes, in which it is represented to be small and rounded; but in the few French specimens which I have had an opportunity of examining, the columellar fold corresponds with that of the English specimens. I presume, therefore, that the form described by M. Deshayes was a modification of the more general form. The shell figured and described by Brard as L. pyramidalis, appears to me, as I have already stated, from its elongated narrow shape, the form of the aperture, and the slight elevation of the fold, to be merely an adult specimen of this species— similar to that represented by fig. 3c and d. The “double suture,” or “narrow spiral riband,” running along the edge of the suture, which Brard mentions as distinguishing L. pyramidalis, frequently occurs in this, as well as in other species ; it is not, however, a constant character in any, and cannot be relied upon as a specific distinction. A form occurs, rather plentifully, in Hordwell Cliff, which Mr. Wood (‘ Lond. Geol. Journ.’ vol. i, p. 118,) has referred to Z. strigosa, (Brogn.) That species, apparently, was proposed from casts or mutilated specimens, and is a questionable PULMONATA. 87 one; M. Deshayes, in fact, (‘Descr. des Coq. Foss.,’ &c. vol. ii, p. 92,) has suggested that it may be merely a variety of Z. dongiscata. The Hordwell shells, like the French, are shorter, and the whorls are more convex; but they present the charac- teristic fold of the present species, of which I consider them to be, therefore, only a variety. Size-—Axis, 2 inches; diameter, 8-10ths of an inch. Localities —Hordwell; Headon Hill; Sconce. French: Belleville; Saint-Ouen ; Fontainebleau; Rochechouart; Veaurs, and Vergnols, near Aurillac; Dax. No. 33. Limnza sutcata. F. &. Hdwards. Tab. XIV, fig. 4a—d. L. testé ovatd ; anfractibus quinque vel sex, convexiusculis, substriatis ; spird mediocre, acutd ; apertura ovatd, spiram in longitudinem superanti ; margine eaterno parum obliquo ; plicd columellari compressa, vie eminenti, profunde sulcata. An ovate shell, composed of five or six slightly convex whorls on which the lines of growth are very conspicuous, imparting a sub-striated appearance to the surface; the spire moderately elevated and pointed. The aperture is ovate, and rather longer than the spire; the outer lip but slightly oblique, and the columellar fold compressed, not very prominent, and more deeply sulcated than in any other species. In general appearance this species resembles L. arenularia; but it may be distin- guished by the flat and deeply sulcated fold. Size-—Axis, rather more than | inch; diameter $ an inch. Localities —Hordwell; Headon Hill. No. 34. Limnmza GipposuLa. Lf. 2. Hdwards. Tab. XIV, fig. 8—e. L. testé ovatd, sub-turritd ; spird brevi, sub-acutd ; anfractibus sex, gibbosulis, ultimo magno, suturis profundis: aperturd acuto-semi-ovali, amplda, basi effusd, bessem totius teste in longitudinem superanti; labro reflexo ; plicd columellari parva, parum tortuosd, sub- compressa, obscuré sulcatd. An ovate sub-turreted shell, with a moderately elevated and rather obtuse spire : volutions six, somewhat gibbous, separated by a deep suture, and, in some specimens, flattened round the upper margin; the last volution is proportionally large. The aperture is semi-oval, dilated in front, acute behind, and exceeds in length two thirds of the whole shell; the inner lip is reflected; the columellar fold small, somewhat compressed, not much twisted, and obscurely sulcated. This species resembles ZL. swé/ata more than any other; but the shell is larger, the spire not so much elevated, the volutions more equally gibbous, the aperture much longer and more effuse at the base, the fold not so much twisted and the outer 88 EOCENE MOLLUSCA. lip not so oblique. From JZ. ¢umida it is separated by the shorter spire and the flat sulcated columella. Size—Axis, 1 inch and 7-10ths; diameter, 9-10ths of an inch nearly. Locality—Headon Hill. No. 35. Limnza susLatTa. Ff. #. Edwards. Tab. XIII, fig. 4a—é. L. testa ovato-acutd, ventricosd: anfractibus sex, conveais, levibus; apertura rotundato- semi-ovali, per-obliqua, ampld, spiram in longitudinem paulo superanti; margine externo reflexiusculo ; plicad columellari compressiusculd, angustd, parum eminenti, valde tortuosd. A smooth, ventricose shell, with a moderately elevated spire, and an acute apex: the six whorls of which it is formed are convex, and separated by a conspicuous but not deep suture; the aperture is roundedly semi-oval, effuse, and a little longer than the spire. The outer lip is very oblique, and slightly reflected; the inner one scarcely extends beyond the aperture; the columella is much twisted, and the small narrow fold is compressed and very little prominent. Owing to the great obliquity of the aperture, the shell must have been carried by the animal with the spire more raised than is usually the case in this genus; from this peculiarity the specific name has been taken. The present species approaches nearly to LZ. giddosula, but the spire is longer and more pointed, the whorls more ventricose, and the aperture shorter in proportion, and more oblique. The greater convexity of the whorls, the shorter spire, the narrow, slightly projecting fold, and the effuse and oblique aperture, distinguish it from L. pyramidalis. Vt appears to be rare. Size-—Axis 14 inch; diameter 8-10ths of an inch. Locality.—Headon Hill. No. 36. Limnaa MIxTa. Ff. £. Hdwards. Tab. XII, fig. 5 a—é. L. testa ovato-acutd ; spird elevatd ; anfractibus sex vel septem, convexiusculis, longi- tudinaliter striatis, ultimo magno, sub-ventricoso: apertura ovali, anticé coarctatd, bessem totius teste in longitudinem fere aquanti ; plicd columellari sub-rectd, angustd, compressi- usculd, parum eminenti, obscure sulcatd. An ovate shell, with a moderately elevated pointed spire; volutions six or seven, slightly convex, almost flat on the upper parts composing the sides of the spire, and marked more strongly than usual in this genus by conspicuous irregular lines of growth ; the body whorl large and rather ventricose. The aperture is oval, contracted in front, and, in length, nearly equal to two thirds of the whole shell; the colu- mellar fold is very little twisted, narrow, slightly flattened, barely prominent, and obscurely sulcated. PULMONATA. 89 I propose this species with hesitation ; it may be only a variety of LZ. pyramidalis or of LZ. gibbosula, but the characters it presents are so mixed, that it is difficult to determine to which species it should be referred. The narrow, flat, and nearly straight fold resembles very closely that of Z. gibbosula; but the spire is more elevated, more pyramidal, the volutions more regularly convex, and the aperture not so effuse. It is distinguished from the typical ZL. pyramidalis, not only by the columellar fold, which in the latter species is larger, more oblique, and more prominent, but also by the flatness of the sides of the spire, and the greater length of the aperture ; and from the variety of that species, by the more contracted aperture. In the character of the spire, and the contracted aperture, it approaches L. fusiformis; but it is separated from it by the columellar fold, which in that species is rounded, prominent, and more twisted. Size.—Axis, 1 inch and 6-10ths; diameter, 8-10ths of an inch. Locality.—Headon Hill. No. 37. Limnza ovuM? Brogn. Tab. XIV, fig. 12 a—4é. LIMNEUS OvuM, Brogn. 1810. Ann. du Mus., vol. xv, p. 374, tab. 22, fig. 13 a, B. -— — Brogn. 1811. Journ. de Phys., &c., p. 422. Lymneus — Férus. 1814. Mém. geol., &c., p. 60, No. 6. Lymnma — Desh. 1824—37. Desc. des coq. foss., &c., vol. ii, p. 97, tab. 11, figs. 15, 16. a — Desh. Encyc. Méth. Vers., vol. ii, p. 361, No. 16. — — RBouill. 1836. Cat. des coq. foss. d’Auv., p. 131, No. 13. L. testé ovali, sub-ventricosd, acuminatd, sub-levi; anfractibus sex, convexis, ultimo magno: apertura mediocri, ad basin sub-dilatatd ; columella marginatd ; plicd columellari parva, compressa, sulcatd, anticé angulatd, parum tortuosd. As I have not had an opportunity of comparing the English with French specimens of this species, the identification cannot be altogether free from doubt. The English shell is nearly smooth, ovate, and sub-ventricose, with a moderately elevated and pointed spire; volutions six or seven, separated by a conspicuous but not deep suture. The aperture is not wide, but is a little dilated in front, and is about half the length of the entire shell: the columellar fold is small, compressed, obscurely sulcated, very shghtly twisted, and scarcely projects into the aperture; the anterior margin presents an acute ridge, formed by the prolongation of the sharp edge of the peristome ; the inner lip is slightly reflected. The aperture is not so contracted in front as M. Deshayes describes that of the French shell to be; it agrees very well with Brogniart’s figure, but not with that given by M. Deshayes, although the latter was taken from Brogniart’s specimen. In other respects the English shells do not appear to differ from the French. x elk = 90 EOCENE MOLLUSCA. In the general contour, and in the proportions of the aperture, the present species closely resembles Z. convera; but the small, flat, sulcated fold separates it from that species. Size.—Axis, 1 inch and 3-10ths; diameter, rather more than 6-10ths of an inch. Localities —Headon Hill. French: Pierrelaie. Sect. 46. Columellar fold rounded or sub-acute. No. 38. Limnza FustFoRMIs. J. Sowerby. Tab. XIII, fig. 8 a—g. Lymnm@a FustFoRMIS, J. Sow. 1818. Min. Con., vol. ii, p. 155, tab. 169, figs. 2-3. LIMNEA — G. Sow. Genera of Shells. = = Lyell and Murch. 1829. Sur les dépéts lacustres, &c., du Cantal. L. testd ovato-acutd, sub-fusiformi, levi; anfractibus septenis vel octonis, sub-planis, ultimo ventricoso: aperturd ovatd, spiram in longitudinem vix equanti ; columella marginata ; plica columellari. rotundatd aut sub-acutd, parum tortuosd. Var. DEFORMIS, (fig. 8 c—e,) testd breviort; anfractibus sex vel septem, ventricosioribus : apertura rotundato-ovali, spiram in longitudinem superantt ; plicd columellari rotundatd, eminentior?. A smooth ovate-acute shell, formed of seven or eight whorls, the upper sides of which are nearly straight, giving a regular conical form to the spire, which is elevated and pointed; the last whorl is ventricose; the lines of growth conspicuous and sharp. The aperture is ovate, moderately large, and nearly as long as the spire; occasionally the anterior part is somewhat contracted, imparting a sub-fusiform shape to the shell. The columellar fold is thick, and, generally, rounded; but sometimes it presents a rather sharp anterior margin; it is slightly and gracefully twisted. Of this species, as of Z. caudata, a variety occurs (fig. 8 c—e) in which the shell is much shorter, the volutions very ventricose, the aperture roundedly ovate, and the fold rounded and prominent. The contraction of the anterior part of the aperture, causing the fusiform shape to which Mr. Sowerby refers, frequently occurs, but it is not by any means a constant character ; in fact, the aperture is more generally somewhat effuse, as represented in the figure 8. This species approaches Z. pyramidalis more nearly than any other of the fossil Limnee; ut the flatness of the sides of the spire, and the rounded fold, are characters by which it may easily be distinguished. The variety resembles the short variety of Z. caudata ; but the whorls are more ventricose, and the fold is not com- pressed and sulcated, as in that species. Size.—Axis, 2 inches nearly; diameter, 8-10ths of an inch. Localities—Hordwell, Headon Hill, Sconce. French: Aurillac in the Cantal. PULMONATA. 91 No. 39. Limnawa tTumipA. Ff. #. Hdwards. Tab. XIII, fig. 6 a—4é. L. testa ovato-acutd, ventricosd, sexies vel septies circumvolutd ; spird elevatd, apice acuminato ; anfractibus convexis, ultimo tumido: apertura ovata, ampla, bessem totius teste in longitudinem fere equanti ; margine columellari reflexo ; plicd parum tortuosd, eminenti, rotundatd, in medio sub-callosd. An ovate, ventricose shell, with an elevated, pointed, rather subulate, spire ; volutions six or seven, the early ones increasing in size slowly, the last two more rapidly; the upper parts forming the sides of the spire are rather flattened, as in L. pyramidalis; the body whorl large and tumid. The aperture is ovate, and in length nearly equal to two thirds of the whole shell; the anterior margin, where it joins the columella, is slightly reflected; the columella itself is not much twisted, and the fold is prominent, round, and thickened towards the middle. This species may be distinguished from Z. gzbdosula, by the round columellar fold and longer spire; and from Z. fusiformis, by the more convex volutions, the tumid body whorl, the longer aperture, and the nearly straight fold. Size—Axis, 1 inch and 8-10ths nearly; diameter, 11-10ths of an inch. Locality—Headon Hill. No. 40. Limn#A COLUMELLARIS. J. Sowerby. Tab. XIII, fig. 9 a—Z. LiMNEA COLUMELLARIS, Sow. 1826. Min. Con., vol. vi, p. 53, t. 528, fig. 2. = = ? Lyell and Mur. 1829. Sur les depéts lacustres, &c., du Cantal. L. testa ovato-ventricosd, sub-turritd, quinquies vel sexies circunwvolutd ; spira brevi, apice acuto; apertura ovali, dilatatd, bessem totius teste in longitudinem Jere equanti; plica columellari rotundatd, callosd, valde contortd, pro-eminenti. I am indebted to Mr. Sowerby for the use of the original specimen described by him of this species. It is a ventricose, oval shell, with a short pointed spire, and formed of five or six very convex whorls, rather depressed at the suture, whence the shell presents a subturreted appearance; the aperture is large, effuse, and nearly as long as two thirds of the whole shell; the thick, callous-like fold is round, very prominent, and much twisted. If it were not for the convexity of the whorls and the size of the aperture, I should be inclined to consider this shell to be only a variety of LZ. fusiformis; and that the unusual contortion of the fold, a character to which individuals of that species occa- sionally approach very nearly, is accidental. But in this species, the pyramidal shape, which always distinguishes the spire of Z. fusiformis, is altogether wanting. From L. tumida, which it resembles in the size of the aperture, it is also separated by the 92 EOCENE MOLLUSCA. greater flatness of the sides of the spire and the less prominent and less oblique fold of that species. It appears to be very scarce. Size.-—Axis, rather more than 1 inch; diameter, 3 an inch. Locality. 'ordwell. French: Aurillac in the Cantal. No. 41. Limnma suB-quADRATA. F. L. Edwards. Tab. XII, fig. 1 a—4. L. testdé ovato-oblongd, turritd, levi; spird mediocrt, apice acuto: anfractibus sex aut septem plano-convevis: apertura ovatd, anticé dilatatd, spiram in longitudinem superanti ; labio incrassato reflexo ; columella subrectd, plicd parvd, viv eminenti, sub-acutd. Shell ovate, oblong, turreted, smooth, with six or seven rather flatly-convex volu- tions; spire moderately elevated, with an acute apex; aperture ovate, somewhat effuse in front, and rather more than half the length of the whole shell; the inner lip thickened, and a little reflected; the columella nearly straight, and presenting a small, rather sharp fold, which scarcely projects into the aperture. The turreted and depressedly convex form of the whorls gives a sub-quadrate appearance to this shell, by which, as well as by its nearly straight columella, and sharp and barely prominent fold, it may be distinguished from Z. conveva, which it most nearly resembles. Size.-—Axis, rather more than 14 inch; diameter, 8-10ths of an inch. Locality—Headon Hill. No. 42. Limnwa convexa. Ff. £. Edwards. Tab. XII, fig. 7 a—4é. L. testé ovato-ventricosd, sexies circumvolutd ; anfractibus convexis, levibus ; spira elevatd, apice sub-acuto: aperturd ovatd, anticé effusd, spiram in longitudinem superanti ; labio reflexo ; plica columellari pro-eminenti, tortuosd, rotundata. An ovate ventricose shell, formed of six smooth convex volutions, with a mode- rately elevated and pointed spire: aperture ovate, effuse in front, and rather longer than the spire; the inner lip slightly reflected; the columellar fold round, prominent, and very oblique. This species somewhat resembles LZ. sub-quadrata ; the whorls, however, are more regularly convex, and do not present the turreted appearance which characterises that shell; and the round columellar fold is much more prominent, and more strongly twisted. In the convexity of the whorls it approaches Z. pyramidalis, but the flat sulcated fold separates that species from this. Size.—Axis, 1 inch and 3-10ths; diameter, 6-10ths of an inch. Locality——Headon Hill. In Mr. D’Urban’s collection. PULMONATA. 93 No. 43. Limnza costTeLiata. &. £. Edwards. Tab. XII, fig. 10 a—é. L. testé ovato-ventricosd, sub-turritd ; spird mediocri, acuminata ; anfractibus quinque vel sex, convevis, longitudinaliter sub-costellatis, et lineis incrementi subtilissimé striatis ; costellis obscuris, irregularibus, remotiusculis : aperturd ovatd, ampla, spiram tn longitudinem superanti ; labio refleco ; plicd columellari viv tortuosd, rotundatd, parum eminentt. The striated Zimuee generally acquire that character from the conspicuous lines of growth; but the present species presents obscure costelle, as well as the striation due to the lines of growth. It is an oval, ventricose, sub-turreted shell, with a moderately elevated spire and pointed apex, and formed of five or six convex volutions, very finely striated by the lines of growth, and also longitudinally costellated; the costella are obscure, irregular, and separated by broad shallow sulci, in which the lines of growth are perceptible. The aperture is ovate, rather dilated, and a little longer than the spire; the columellar margin strongly reflected, and the fold rounded, slightly twisted, and but little prominent. Independently of its costellated character, this species presents differences which prevent its bemg confounded either with Z. strigosa (Brogn.), or L. substriata (Desh.). In the first species, the shell is more elongated, the aperture smaller, and the colu- mellar fold resembles that of LZ. /ongiscata, of which I think it is merely a variety; in the latter, the spire is more elevated, the aperture much contracted in front, and altogether narrower; and the fold is prominent and strongly twisted. The present appears to be a well-marked species. Size.—Axis, rather more than 1 inch; diameter, 4-10ths of an inch. Localities —Hordwell ; Headon Hill. No. 44. Limnama FABuLUM. Brogniart. Tab. XIV, fig. 10 a—d. Limnevs FaBuLuM. Brogn. 1810. Ann. du Mus., vol. xv, p. 375, t. 22, fig. 16. — — Brogn. 1811. Journ. de Phys., &e. vol. Ixxii, p. 423. LyMNEUS — Fér. 1814. Mém. geol., p. 61, No. 13. LIMNEA = ? Lyell and Mure. 1829. Sur les depdts lacust. tert. du Cantal. LymN@A FABULA. Desh. 1824—37. Desc. des coq. foss., &c., vol. il, p. 96; t. 11, figs. 11-12. — — Desh. 1830. Ency. Méth. Vers., vol. 11, p. 361. LyMNzEUs FABULUM. Defr. 1835. Dict. des Sci. Nat., vol. xxvi, p. 462. Limyza Faputa. Myst. 1836. Rech. coq. foss. de Hoesselt, &e., p. 20, No. 49. LyMN#A FaBULA. Desh. 1838. 2d edit. Lam. Hist. Nat., vol. viii, p. 223, No. 9. Limnzus rapota? Nyst. 1843. Desc. des coq. &c. foss. des Terr. tert. de Belg., p. 469, t. 38, fig. 18. L. testé ovato-ventricosd, levi, acuminata ; anfractibus quinque vel sex, conveaiusculis: apertura ovato-acutd ; plicd columellari sub-acutd, parum tortuosd. 94 EOCENE MOLLUSCA. A smooth, ovate, ventricose shell, with a short pointed spire, and formed of five or six slightly convex whorls; the aperture pointedly ovate, and the columellar fold somewhat angular and prominent, but not much twisted. I have not had an opportunity of comparing the English with the French shells, and I have therefore some hesitation in pronouncing as to their identity. My specimens, however, agree very well with the description and figures given by M. Deshayes, (which it must be remembered are taken from casts merely,) except that the French shell is described as formed of four whorls only, and as having the aperture contracted at the base; but the figures show six whorls, and the aperture, as drawn, is scarcely more contracted than that of the English shell. Size.—Axis, rather more than 8-l0ths of an inch; diameter, 4-l0ths of an inch. Localities —Hordwell. French: Jouy; Saint-Prix, Montmorency; Pierrelaic and Lavergnol in the Cantal. Belgian: Kleyn-Spauwen. No. 45. Limnawa cinota. F&. #. Edwards. Tab. XIV, fig. 5 a—é. L. testa elongato-ovatd, sub-turritd, sexies vel septies circumvoluta; spird exserta, acuminata; anfractibus convexis, substriatis: apertura rotundato-ovatd, ampla, spiram in longitudinem @quanti; plicd columellari parvd, angustd, rotundatd, parum tortuosa, proeminenti. An elongated ovate shell, with an elevated pointed spire; volutions six or seven, very convex, almost ventricose, the edges of which are depressed along the suture, and, generally, present a sharp stria running round them, parallel with and at a short distance below the suture,—similar to that mentioned by Brard as characterising his L. pyramidale: the lines of growth are so strongly marked that the surface of the shell almost appears to be striated. The aperture is roundedly ovate, somewhat effuse, and barely exceeds the spire in length; the columellar fold is narrow, rounded, not much twisted, and prominent. The line of suture frequently runs below the wide part of the whorl, giving a distorted appearance, resembling that which is sometimes seen in ZL. longiscata, and in fact the present shell presents a close analogy with that species. It is, however, distinguished from JZ. longiscata, as well as from L. pyramidalis (Desh.), by the round columellar fold, and the greater convexity of the whorls. Size-—Axis, 14 inch; diameter, rather more than } an inch. Locality—Headon Hill. PULMONATA. 95 No. 46. Limnza anGusta. F. 2. Edwards. Tab. XIV, fig. 6 a—4é. L. testa angustd, elongata, sub-turrita, quinquies vel sexies circumvolutd ; spird elevata, acuminata ; anfractibus convexis, lineis incrementi obscuré striatis : apertura ovato-oblonga, anticé sub-dilatatd, spiram in longitudinem parum superanti; plicd columellari crassd, tereti, parum eminenti, sub-tortuosd. If it were not for the thick, round, columellar fold, and the elongated aperture, I should refer this species to L. longiscata, which it much resembles. It is a narrow, elongated, sub-turreted shell, formed of five or six convex volutions, obscurely striated by the lines of growth; the spire elevated and pointed. The aperture is a longish oval, equal to half the length of the shell, and rather spread out in front ; the columellar fold is thick, round, not very prominent, and but slightly twisted. The long narrow shape of this shell separates it from every species except L. longiscata ; from the latter shell it is easily distinguished by the fold, so opposite in character to the broad, flat, sulcated fold which characterises that species. Size-—Axis, 1j inch; diameter, not quite 3 an inch. Localities —Hordwell; Headon Hill. No. 47. LIMNHA ARENULARIA. Brard. Tab. XIV, fig. 13 a—d. LymN&E pgs Gres. Brard. 1810. Ann. du Mus., vol. xv, p. 409, t. 24, fig. 5-6. LyMNEUS ARENULARIUS. Féruss. 1814. Meém. geol. &. p. 61, No. 15. LYMN#A ARENULARIA. Desh. 1824—37. Desc. des coq. foss., &c., vol. ii., 1 CB aul figs. 7-8. L. testa ovato-acuminatd, sub-turrita, levi; anfractibus septenis, convexiusculis, suturis conspicuis : apertura ampld, semi-ovali, spiram in longitudinem superanti ; plicd columellari rotundatd, minima, parum contortd, sub-proeminenti. A smooth, ovate, oblong sub-turreted shell, with a moderately elevated and taper spire; volutions seven or eight, slightly convex, separated by a conspicuous, but not deep, suture, and occasionally striated by faint lines of growth: the aperture rather large, semi-oval, a little dilated in front, and longer than the spire; the columellar fold rounded, small, slightly twisted, and not very prominent. The English shells correspond so nearly with M. Deshayes’s figures, and with some French specimens, for which I am indebted to that gentleman, as not to leave any doubt as to this identification, notwithstanding that M. Deshayes describes the aperture as very oblique, and the columellar fold as much twisted, characters which I have not found prominent either in the English or French specimens. Size.—Axis, 4-10ths of an inch; diameter, 7-20ths of an inch. Localities. —Hordwell; Headon Hill. french: Beauchamp, near Pointoise, Valmondois. 96 EOCENE MOLLUSCA. No. 48. LimnzA MINIMA. Sowerby. Tab. XIV, fig. 9 a—c. LymN#A MINIMA. Sow. 1817. Min. Con. vol. ii, p. 156, t. 169, fig. 1. L. testé minimd, ovato-elongatd, levi; anfractibus quinque aut sex, convexiusculis : apertura ovali, spiram in longitudinem vie aquanti ; margine columellari reflexo ; plicd sub- recta, rotundatd, parum eminentt. It is not unlikely that this, as Mr. Sowerby has suggested, may be the young shell of some species already described, probably of LZ. arenularia, to which, in its regularly taper spire and rounded fold, it presents a close approximation. It is a very small, smooth, elongated, ovate shell, with five or six rather convex volutions, separated by a moderately deep suture : the aperture is ovate, and rather less than half the length of the entire shell; the inner lip is strongly reflected, and the fold is round, nearly straight, and very little prominent. The figures are taken from the original specimen described by Mr. Sowerby in ‘Mineral Conchology.’ Size.—Axis, 3-10ths of an inch nearly; diameter, 2-10ths nearly. Locality Headon Hill. No. 49. Limnza REcTA. Ff. LH. Edwards. Tab. XIV, fig. 7 a—4é. L. testé ovato-ventricosd, sub-turritd ; spird mediocri, apice acuto; anfractibus sex aut septem, convexis: apertura ovali, ampld, anticé dilatatd, longiori quam spira; margine columellari sub-reflexo ; plicd parvd, viz tortuosd, parum eminenti. The convexity of the whorls, the pointed spire, and the nearly straight rounded fold, distinguish this from every other fossil species. It is a short ovate shell, with a moderately elevated spire, and an acute apex; volutions six or seven, very convex, the last one rather ventricose: the aperture large, of a roundedly ovate form, effuse in front, and longer than the spire; the inner lip slightly reflected, and the small rounded fold nearly straight, and scarcely impinging upon the aperture. This shell much resembles ZL. ovwm (Brogn.); but the volutions are fewer and more ventricose, and the aperture is more effuse. It does not appear to me to be referable to any other species; and I have therefore, although reluctantly, described it as a distinct species. Stze.—Axis, 1 inch and 1-10th; diameter, 5-10ths of an inch. Locality.—Headon Hill. PULMONATA. 97 " No. 50. Limnz4 TENUIS. &. HL. Edwards. Tab. XIV, fig. 11 a—é. L. testa tenui, ovato-ventricosd, sub-turrita ; anfractibus sex, conveais, ultimo magno ; apice acuto: aperturd ovata, effusd, in longitudinem bessem totius teste feré equanti; plicd columellari brevi, angustd, rotundatd, parum tortuosa. This species presents so close an analogy with L. fwmida, that it would be difficult to separate the two, if it were not for the great difference in size. The shell is very thin, ovate, and formed of six convex volutions, depressed round the suture, which character imparts to it a sub-turreted appearance; the spire is somewhat elevated and pointed ; the body-whorl large and ventricose: the aperture ovate, effuse, and nearly as long as two thirds of the entire shell; the columellar fold short, narrow, rounded, and not much twisted. Size.—Axis, 8-10ths of an inch; diameter, 4-10ths of an inch. Locality —Headon Hill. Genus 13th. PLANoRBIs. Geoffroy. Coretus, Adanson, 1757. Pranorzis, Geoffroy, 1767; Guettard, 1770; Miiller, 1773-4. Gen. Char.—Shell discoidal, spire depressed ; volutions apparent above and below, convoluted upon a nearly horizontal plane, thin, generally smooth, ventricose, some- times carinated: aperture simple, lunate, crescent-shaped or sub-quadrate, impinged upon by the preceding volution; outer lip generally thin, sharp edged, sometimes thickened or reflected; columellar lip slightly spreading over the body whorl. No operculum. The animals belonging to this genus were placed by Linnzeus among the Helices ; they had, however, been separated, as a distinct group, by Lister, nearly a century previously, and formed the third section of the Lacustrine shells of that author. Shortly before the publication of the Systema Nature, Adanson described a small species to which he gave the generic name Coretus. The genus was afterwards defined by Geoffroy under the present name Planorbis ; and Miiller, to whom it has been gene- rally attributed, only adopted Geoffroy’s name. The animal of Planorbis is elongated, slender, and strongly rolled up; the head is furnished with two long contractile tentacles, at the internal bases of which the eyes are placed; the orifices are on the left side; the organs of generation distinct. Whether the shell of Planoréis is dextral or sinistral is a question which has been much discussed, and, by some authors, is considered as still undecided. By Linnzus, Miiller, and subsequent writers to the time of Cuvier, it was regarded as dextral, and was described as supra umbilicata. The transposition in P. corneus of the "13 98 EOCENE MOLLUSCA. orifices and the heart, all of which are on the side contrary to that in which they are placed in the animals of dextral shells, induced Cuvier to consider that species as sinistral : and in this opinion many eminent naturalists have concurred. M. Desmoulins, however, has ascertained, by a careful anatomy of the animal of P. corneus, that, although the orifices and the heart have an abnormal position, the organs of digestion and generation, in fact, retain the position they hold in dextral molluscs; and that author, therefore, maintains that nearly all the known species of Planorbis, as well living as fossil, are dextral. M. Deshayes concurs in this opinion; and, after remark- ing that the upper side may be distinguished from the under side by the obliquity of the aperture, the superior margin of which is more produced, cites the observations of M. Desmoulins as explaining the apparent anomaly of a sinistral animal in a dextral shell, and how, in reality, the animal is dextral as well as the shell; there not being any other derangement in the relation of its organs than with regard to the heart and the termination of the digestive and generative organs. With regard to the shell, it will be seen at once, on observing the manner in which it is carried by the animal, that it is dextral, and that, as Mr. Benson has stated,* if it be viewed practically as sinistral, and placed as such, the animal will be on its back, and will have to twist its body half round in order to gain the ground with its foot. Mr. Benson, therefore, proposes to consider that face as containing the apex, in discoidal shells, which is con- tiguous to the back of the animal; and, he adds, this side may invariably be known in Planorlus by the greater projection of the lip in that part, by the deeper depression of the central umbilicus, and by the more considerable involutions of the whorls occasioning a greater depth of suture. Mr. G. Sowerby, on the other hand, assertst that the shell is sinistral, and that it is only needful to observe on which side of the shell the very apex of the spire is actually to be seen, and, taking that side for the upper, im conformity with the strict rules of analogy, it will immediately be evident that the aperture is on the left side. This criterion, however, is seldom available ; for, in general, the apex is concealed by the involution of the whorls, and the shell presents, on each face, what may be easily mistaken for an umbilicus; and the diffi- culty in determining which face contains the apex, and which the true umbilicus, is not removed. It is well known that testaceous molluscs, when placed in conditions unfavorable to healthy development, frequently depart from their normal form; and that their shells, in consequence, are distorted, and become what are usually called monstrosities. Thus, in Planordis, the animal, under such conditions, frequently loses, to a greater or less degree, its strong convolution on a horizontal plane; and the shell assumes, in conformity, a more or less elongated spiral form, with an elevated apex. M. Desmoulins cites these monstrosities in support of his opinion, observing that, when they occur, the whorls gradyally glide from left to right, down the imaginary * Journal Asiat. Soc. Bengal, vol. v, p. 744. + Genera of Shells. Gen. Planorbis. PULMONATA. — oe x axis. A series of such distorted specimens of P. complanatus, taken from a pond near Swansea, formed, I believe, by the waste water from a steam-engine, and of a high temperature, is in the British Museum. These specimens have all assumed an elevated spiral form; and the aperture is in every case dextral. Several specimens of P. vortea, in Mr. Sowerby’s Museum, are similarly distorted ; and in them also the apertures are dextral. On the whole, the better opinion appears to be that the shell, as well as the animal, is dextral, notwithstanding the abnormal position of the heart and the orifices; and in the following descriptions, therefore, I have considered the shell as dextral, and I have applied the term wpper to that disc which is uppermost when the shell is placed with the mouth on the right side of the spectator, and the term wnder to the opposite disc. The Planorées live in fresh water; more frequently in stagnant water or standing pools, although, occasionally, they are found in gentle streams. They are widely diffused, but abound principally in temperate climates. I believe that at present there is not any species known as living in salt or brackish waters; and the specimens found in the crag formation, and described by Mr. Wood, are referred to recent species which are known to be pure fresh-water animals; and these shells are therefore consi- dered to have been accidentally introduced. Four species also occur in the estuarine or fluvio-marine deposits of the Eocene epoch: viz., P. hemistoma (Sow.); P. obtusus (Sow.); P. biangulatus (nov. spec.); and P. elegans (nov. spec.); but, like the crag specimens, they have, probably, been depo- sited there by the agency of some river: they all occur in the pure fresh-water or the transition formations. Fossil species are numerous, but they abound principally in the formations of the tertiary epoch; Prof. E. Forbes, however, states, (Brit. Mol., vol. iii, p. 146,) that representatives of the genus, differing but slightly from species still living, are found in fresh-water strata of even the oolitic epoch. No. 51. PLANORBIS EUOMPHALUS. Sowerby. Tab. XV, fig. 6 a—c. PLANORBIS EUOMPHALUS. J. Sowerby. Min. Con., vol. ii, p. 92, t. 140, figs. 7—9. = = G. Sowerby. Genera of Shells, fig. 5. — — Deshayes. Lam. Hist. Nat., 2d edit., vol. viii, p. 397, No. 9. P. testé supra sub-pland, ad peripheriam angulatd, subtus late et profundé cavata ; anfractibus sex, sub-trigonis, vie involventibus, transversim lineis incrementi notatis, aliquandoque concentricé striatis ; subtis ad marginem umbilicalem obtuse angulatis; striis concentricis numerosis, irregularibus : apertura per-obliqud. This well-known species, which at present appears to be confined to the fresh- water formations of England, is easily distinguished from the cther fossil Plaxordes. It is a large discoidal shell, nearly flat on the upper face, and presenting a wide and 100 EOCENE MOLLUSCA. deep umbilical cavity beneath ; the six or seven volutions of which the shell is formed, are flat, or nearly so, above; convex below; and each but slightly embracing the preceding volution; the apex is concealed by the involution of the whorls. A clearly defined and rather acute angle, almost forming a keel, runs round the periphery of the shell, and separates the upper from the under disc. This angle is always very conspicuous in young shells; but as they approach maturity, it becomes more and more obtuse, and frequently altogether disappears; the whorls then assume a trans- versely oval form, approaching nearly to that presented by P. rotundatus. On the under surface, the inner margins of the whorls are bent rather suddenly towards the preceding whorl, and present, in consequence, an obtuse angle, which runs round and defines the umbilicus. Transverse lines of growth are very conspicuous; and frequently the surface of the shell also presents more or less numerous concentric raised lines, some of which are larger and more prominent than the rest. The aperture is sub-trigonal, slightly impinged upon by the preceding volution, and very oblique. This species presents a general resemblance to P. rotundatus; but, even when the characteristic angle has become obsolete, it may easily be distinguished by the greater breadth, and the flatness of the upper surfaces, of the whorls, the much larger concavity on the under side of the shell, and the subtrigonal and more oblique aperture. From P. discus it is separated by the more compressed form of that species, caused by the greater width of the whorls, and the comparative flatness of their under sides ; and in that species the whorls are more embracing than in this. Size-—Diameter, 1 inch and 6-10ths. Localities—Headon Hill; Hordwell. No. 52. PLANoORBIS ROTUNDATUS. Brard. Tab. XV, fig. 4 a—e. PLANoRBE ARRONDI. Brard. 1809. Ann. du Mus,, vol. xiv, p. 433, t. 27, figs. 19, 20. PLANORBIS ROTUNDATUS, Brogn. 1810. Ib., vol. xv, p. 370, t. 22, figs. 4, 5. —_ —_ Tb. 1811. Jour. de Phys., vol. Ixxii, p. 419, figs. 4, 5. — SIMILIs. Fér. 1814. Mem. geol., p. 61, No. 1. = RoTUNDATUS. Fér. 1814. Ib., No. 2, var. a. = = Desh. 1824—37. Desc. des coq. foss., vel. i, p. 83, t. 9, figs. 7, 8. — a Desh. 1824—37. Encycl. Meth. Vers., &c., vol. i, p. 778, No. 2. — — Bowd. Elem. of Conch., t. iv, fig. 7. — — Lyell and Mur. 1829. Sur les depots, &c. du Cantal. — —_ Bouillet. Desc. hist. et scient. de la Haute Auver., p. 18, figs. 6, 7. — ~ Ib. 1836. Cat. des coq. viv. et foss. de l Auver., p. 115, No. 2. —_ —_ Gratel. 1838. Cat. des deb. foss., &c., du bassin de la Gironde, i p. 33, No. 102. = = Desh. 1838. Lam. Hist. Nat., 2d edit., vol. viii, p. 394, No. 1. PULMONATA. 101 P. testé levi sub-striatdve, superné sub-pland, subtus concavd ; anfractibus sex vel septem, rotundatis, viv involventibus, inferné ad marginem umbilicalem sub-angulatis ; suturis profundis : apertura parum obliqua. A rather large shell, formed of six or seven nearly round volutions, separated by a deep suture, and each slightly impinged upon by the preceding one; the volutions are flatly convex on the upper sides, convex beneath, and, like those of P. exomphalus, present an angle running round the inner margins near the umbilicus, which, as the shell approaches maturity, becomes almost obsolete. The upper face is nearly flat ; while the under side presents a moderately deep and wide concavity. The aperture is transversely oval, and but slightly oblique. The strize of growth are very conspi- cuous; and occasionally, although very rarely, the shells present fine concentric lines, similar to those which characterise ?. ewomphalus ; in this species, however, the lines are finer and more crowded, and seldom extend beyond the first three or four volutions. Brard states that, in P. arrondi, the whorls are perfectly round, and do not impinge upon the succeeding whorls; and in these respects his shell does not agree with the English specimens; but the figures, apparently, are taken from a cast, and the dis- agreement may probably be attributed to that circumstance. Brogniart’s fig. 4, (var. A, of that author,) agrees very well with our specimens, except that the aperture is more oblique. In the figure given by M. Deshayes, the whorls are wider and more flattened on the upper surface, and the upper margin of the aperture appears to be more produced than in any English specimen I have seen; the shell, too, is larger than our shells, and, in fact, strongly resembles those specimens of P. ewomphalus in which the characteristic angle round the whorls has become obsolete. The general resemblance and the distinctions between the present species and the recent P. corneus, have been pointed out by the French authors cited; and, on com- paring the two, it will be seen that in the latter species the whorls are fewer, rounder, and enlarge more rapidly, and that in consequence, the shell is deeper and more largely umbilicated than the fossil species. MM. Ferussac and Deshayes mention a variety (probably the var. B of Brogniart) in which the shell is smaller, rather more compressed, and nearly equally concave above and below; | have not met with this variety among the English specimens. Size.—Diameter, 1 inch and 2-10ths. Localities —English: Sconce; Headon Hill; Hordwell. French: Aurillac, La Vissiere, Lavergnol, in the Cantal; Saint-Prix; Palaiseau, Milon near Versailles; Triel; Fontainbleau; La Villette. 102 EOCENE MOLLUSCA. No. 53. PLANORBIS oBTUSUS. Sowerby. Tab. XV, fig. 1 a—e. PLANORBIS OBTUSUS. Sow. 1818. Min. Con., vol. ii, p. 91, t. 110, fig. 3. P. testd depressd, levi; superné convexiusculd, subtis concava: anfractibus quinis, obtusé-ovalibus, sese partim involventibus; suturis profundis : aperturd per-obliqua, obcordata. This very pretty shell has a smooth, shining, nearly polished surface ; it is depressed, nearly flat on the upper side, and moderately concave beneath. The volutions are five, separated by a deep suture, slightly convex on both faces, but rather more compressed on the under side than on the upper, obtusely rounded at the periphery, and each nearly half concealed by the succeeding volution. The aperture is very oblique and bluntly heart-shaped. In the general form and rounded whorls, this species much resembles P. sparna- censis (Desh.), but the whorls are not so numerous, and the aperture is more oblique. The lenticular form and angulated margin of P. /ezs, will prevent its being confounded with that species. Size.—Diameter, 7-10ths of an inch. Localities —Sconce ; Headon Hill; Upper mar., Hordwell. No. 54. Pranorsis piscus. F. 2. Edwards. Tab. XV, fig. 7 a—d. P. testd valde compressd, quinguies circumvolutd, superné pland, subtus profunde cavatd : anfractibus sex, rapide crescentibus, parum involventibus, subtus convexiusculis, ad marginem umbilicalem angulatis: apertura per-obliqua, elongato-cordata. This well-marked species appears to be peculiar to the fresh-water formation at Sconce. It is a much compressed discoidal shell, nearly flat on the upper side and deeply hollowed out below. The five or six whorls of which it is formed enlarge rapidly, and each is slightly embraced by the succeeding one; they are much flattened above, slightly convex below, and obtusely rounded at the outer edge. In the young state, the inner margin is bent rather abruptly towards the preceding whorl, and pre- sents an obtuse angle which defines the umbilicus, similar to that presented by P. euomphalus and P. rotundatus. As the shell approaches maturity, the under side assumes an almost regularly convex form, and the angle becomes obsolete. The aperture is very oblique, and of an elongated heart-shape. The species which most resemble the present are P. evomphalus and P. oligyratus. From the first of these, it is distinguished by its more compressed discoidal form, and the rounded periphery. The whorls also enlarge more rapidly, and are consequently fewer and broader; and they embrace more of the preceding one than do those of P. cuomphalus. The umbilical cavity also is not so wide. It is more difficult to PULMONATA. 103 separate the present species, in the young state, from P. oligyratus ; but, in the latter, the axis is longer, the whorls are more convex on the upper side, and the obtuse angle which runs round the periphery, near the upper surface, gives a subtrigonal form to the whorls and the aperture, quite distinct from the transversely oval form in the present species. Casts of this Planorbis occur in great abundance, but specimens with the shell preserved are extremely rare. Size.—Diameter, 1 inch and 6-10ths. Locality Sconce. No 55. PLANoRBIS OLIGYRATUS. F. HL. Edwards. Tab. XV, fig. 3 a—e. P. testdé superné sub-pland, subtus cavatd: anfractibus quaternis, rapide crescentibus, parum involventibus, ad peripheriam obtuse angulatis: subtus ad marginem umbilicalem angulatis : apertura sub-trigond, parum obliquad. The present, like the preceding species, is apparently confined to the fresh-water formation at Sconce; but it is not so plentiful as P. discus. It is a moderately-sized shell, formed of four rapidly increasing whorls, somewhat convex above, and rather acutely angulated round the inner margins on the under side, just above the umbilicus. The periphery, near the upper surface, presents an obtuse angle, from which the whorls slope rather abruptly towards the umbilicus, assuming, in consequence, a sub- trigonal form. The aperture is slightly oblique and bluntly obcordate, in consequence of its being impinged upon by the preceding whorl. The umbilical cavity is deep, but not very wide. This species somewhat resembles the young shell of P. discus; but the greater convexity of the under side of the whorls, and the small degree of obliquity, and the shape of the aperture, will distinguish it. The adult shell of P. discus is easily sepa- rated by its greater size and compression. The specimens ordinarily found are, like those of the preceding species, casts merely; with the shell preserved they are very rare. ~ Size.-—Diameter, 7-10ths of an inch. Locality.— Sconce. No. 56. PLANORBIS PLATYSTOoMA. WS. Wood. Tab. XV, fig. 2 a—d. PLaNnorsis PLatystoma. S. Wood. Lond. Geol. Journ., vol. i, p. 118. P. testé parva, utrinque fere equaliter cavatd; anfractibus trinis, rotundatis, tumidis, rapide crescentibus, supra depressiusculis, subtus conveais, singulo fere dimidium antecedentis involventi: apertura magnd, per-obliqui, obtuse obcordatd, peristomate aliquando reflexo. 104 EOCENE MOLLUSCA. A small smooth shell, formed of three tumid rapidly-enlarging whorls, each embracing about one half of the preceding one ; the whorls are rounded, almost equally convex above and below, but a little compressed on the upper side. The apex is wholly concealed by the involution of the whorls. The aperture is wide, very oblique, and bluntly heart-shaped; sometimes, in the adult shell, the peristome is reflected. The upper side is slightly concave, and the under side presents a wide and moderately deep umbilicus. This species, which appears to have been first noticed by Mr. Wood, is so well marked that it cannot be confounded with any other. It somewhat resembles the young shell of P. oligyratus ; but, in the latter shell, the whorls are not so embracing, the upper side is more flattened, and the under side is not so regularly convex. The aperture, also, is narrower and much less oblique. The reflected lip, which frequently occurs in the present species, evidences the maturity of the shell; and the difference between the size of such specimens and that of the fully formed shell of P. oligyratus confirms the separation of the two species. In addition to these distinctions, it may be stated that the present species is found plentifully both in Headon Hill and at Hordwell; but that as yet no specimen of P. oligyratus has heen found at either of those localities. Size.—Diameter 3-10ths of an inch. Localities —Hordwell; Headon Hill; and Sconce. No. 57. PLANORBIS LENS. Brogniart. Tab. XV, fig. 8 a—d. PLANORBIS LENS. Brogn. 1810. Ann. du Mus., vol. xv, p. 372, t. 22, fig. 9. _— — Tb. 1811. Journ. de Phys., &e. vol. Ixxii, p. 421. — — Fér. 1814. Mém. geol., p. 61, No. 10. — — Sow. 1818. Min. Con., vol. ii, p. 91, t. 140, fig. 4. —_— — Desh. 1824—37. Desc. des coq. foss., &c., vol. ii, p. 87, t. 9, figs. 11—13. — — Bouill. 1836, Catal. des coq. foss. de ’ Auvergne, p. 115. — — Desh. Ency. Méth. Vers., &c., vol. iii, p. 783, No. 16. — — Ib. 1838. Lam. Hist. Nat., 2d edit., vol. viii, p. 396, No. 7. — Morris. 1843. Cat. Brit. Foss., p. 156. An. PLANORBE ANGULEUX? Brard. 1810. Ann. du Mus,, vol. xiv, p. 435, t. 27, figs. 23-4. P. testé parva, lenticulart, levi, utrinque parum, sed plus superne quam subtus, cavata; anfractibus quaternis, singulo fere dimidium antecedentis involventi ; supra convexiusculis, subtus plano-conveais, ad peripheriam acute angulatis ; aperturé parum obliqud, elongato- cordata. Mr. Sowerby, when he gave the name /. /ens to a British fossil, appears not to have been aware that that name had previously been dedicated by Brogniart to a shell from the Paris basin; but, by a singular coincidence, the shells described by PULMONATA. 105 these authors appear to agree so closely that they must be referred to the same species. I have not, it is true, had an opportunity of comparing the English with the French shells; the identification, therefore, rests entirely on the figures and descriptions given by MM. Brogniart and Deshayes; but, forming my opinion from them, I cannot see any sufficient reason for considering the English shells as distinct. The present species is a small lenticular shell, slightly concave on each disc, but more so on the upper than on the under side: the whorls are four or five, each embracing nearly one half of the preceding whorl; they are slightly convex on both surfaces, but more so above than beneath, and acutely angulated round the periphery, a little below the middle of the whorl. The aperture is of an elongated heart-shape, and not very oblique. Brogniart describes his shell as swelled out (bombé) and lenticular rather than umbilicated; and this, owing to the slight concavity of the discs, may be taken as the general character of the English shell. M. Deshayes, whose figures are drawn from the original specimen, states that in Brogniart’s figure the shell is represented with the sides too much swelled out, and with the marginal angle too near the middle. Making due allowance for these errors, it will be seen that the contour of the shell and the form of the aperture represented by Brogniart’s middle figure, agree very well with those of the English specimens.* In the figure given by Mr. Sowerby the aperture is represented as very obcordate, and it conveys the idea of the whorls and the shell being more convex than they really are. M. Bronn, in his ‘ Lethea geognostica,’ (p. 1011,) states that the shell described by Mr. Sowerby is more depressed than that of the typical P. dens, and he refers it to a distinct species, which he has named P. Sowerbyi. I fear that M. Bronn had not authentic specimens of our P. lens before him ; for the figures he has given (Tab. XL, fig. 17 a—c,) do not correctly represent that shell; but they, as well as his description, agree closely with another of our Eocene Planorbes, which I have therefore referred to his species. The P. /ens of ‘Mineral Conchology’ appears to me, as I have already stated, to correspond so closely with Brogniart’s P. /ens, that the two cannot be separated. Férussac quotes Brard’s Planorbe anguleux as a synonym; but whether the present species really is the same cannot well be determined without reference to the original specimen, as both the description and the figure given by Brard are too imperfect for the purpose of identification. I have, however, followed the example of MM. Brogniart and Deshayes, in quoting Brard with a query. Size—Diameter, 3-10ths of an inch nearly. Localities—Hordwell, and Headon Hill, where it is moderately plentiful. rench: Saint-Chaumont, Pantin, Limagne, Cournon. * Judging from the aperture, Brogniart’s figures are reversed, probably owing to an oversight of the artist. “14 106 EOCENE MOLLUSCA. No. 58. PranorBis TRoPIS. Ff. #. Hdwards. Tab. XV, fig. 10 a—d. P. testé minutd, depressd, levi, superne parum concavd, subtus late umbilicata : anfrac- tibus quaternis vel quinis, lente crescentibus, supra convexiusculis, infra sub-planis, ad peripheriam carinatis, singulo dimidium antecedentis obtegenti: apertura obliqua, angusti- cordatia. Mr. Wood (‘London Geol. Journ.,’ vol. i, p. 118,) has referred this species to P. planulatus (Desh.), observing, however, that “the figure by Deshayes is not so flat and carinated as the English specimens, which more resemble. the P. evacutus (Gould).” I have not seen any French specimens of P. planulatus; but, on comparing the English shells with the description and figures given by M. Deshayes, I cannot concur in referring them to that species. P. ¢ropis is a minute, compressed, polished shell, a little sunk round the apex, and widely but not deeply umbilicated; the four or five volutions, of which it is formed, are slightly convex above, nearly flat beneath, and compressed near the outer margin so as to present a prominent keel, which runs round the periphery a little below the middle of the whorl. The whorls are much concealed, each embracing about one half of the preceding one; the aperture is very oblique and of a longish heart shape. Although the general resemblance between this species and P. planulatus must be admitted, yet there are, I think, sufficient grounds for specific distinction. In the present species, the whorls increase more slowly and are more concealed ; they are not so convex above nor so flat beneath, and, consequently, the keel is near the middle of the shell, and the aperture assumes an elongated heart shape; whereas, in P. planu- latus, owing to the greater flatness of the under surface of the whorls, the marginal angle (for, judging from the figure given by M. Deshayes, the term /ee/ is not applicable,) runs round the base of the shell, and the aperture is sub-trigonal. The English shell also appears to be smaller than the French one. On these grounds, notwithstanding the distrust I feel at dissenting from Mr. Wood’s opinion, I consider the present to be a distinct species. In the character and position of the keel, P. tropis corresponds with P. evacutus; but in the recent shell, the whorls enlarge more rapidly and are more convex, both above and below; the umbilicus is deeper, and the aperture wider, than in the present species. Size.—Diameter, not quite 3-20ths of an inch. Locality.—Hordwell. No. 50. PLANORBIS HEMISTOMA. Sowerby. Tab. XV, fig. 11 a—d. PranorBis Hemistoma. Sowerby. 1818. Min. Conch., vol. ii, p. 91; t. 140, fig. 6. P. testa minutd, depressd, levi, superne profundé cavatd, subtus subpland, ter quaterve circumvolutd ; anfractibus vie involventibus, ad peripheriam sub-angulatis, supra conveat- PULMONATA. 107 usculis, ad marginem sinistram acute angulatis; infra subplanis; aperturd parum obliqud subtrigonda. A minute, smooth, much depressed shell, deeply concave on the upper side, almost flat on the under side: volutions three or four, very slightly convex above, nearly flat beneath, and compressed, almost angulated at the periphery above the middle of the shell. The whorls can scarcely be described as embracing, inasmuch as the under surface is wholly exposed, although the upper surface is partly concealed by the succeeding whorl; the inner margin is bent, rather abruptly, towards the apex, and presents a conspicuous angle, which runs round the cavity. The aperture is oblique, but not much so, and subtrigonal, having the lower margin rounded. This species somewhat resembles P. elegans; but it is smaller and more compressed, and the subangulated periphery and flatness of the whorls impart a triangular form to the aperture very different from the roundish, heart-shaped aperture of that species. In P. biangulatus, the whorls are more convex, and the aperture is consequently almost obcordate. Size—Diameter, 1-10th of an inch nearly. Localities—Hordwell; Plumstead; Sundridge; Rotherhithe. No. 60. PLANORBIS ELEGANS. J. LZ. Edwards. Tab. XV, fig. 12 a—d. P. testd minuta, politd, superne profunde cavatd, subtus parum cavata ; quater vel quinquies circumvolutd, anfractibus lineis incrementi notatis, ad peripheriam rotundatis ; supra convexis, ad marginem sinistram angulatis ; infra convewxiusculis ; singulo fere trientem antecedentis obtegenti: apertura parum obliqud, obcordatda. This very elegant little Planorbis is found in great abundance on Headon Hill, in a deposit immediately above the upper fluvio-marine formation, associated with Bulimus politus, Melanopsis carinatus, Melanopsis buccinoidea, a species of Neritina, as yet undescribed, and AZelania muricata. It is a small polished shell, deeply but not widely hollowed out on the upper disc, and slightly concave, almost flat, beneath: volutions four or five, rounded on the periphery, marked by conspicuous lines of growth nearly perpendicular to the axis, very convex, and presenting a sharpish angle running round the inner margin, on the upper surface, and but slightly convex beneath ; each volution embraces nearly a third of the one preceding it. The aperture is of a roundish heart shape, and very slightly oblique. Size.—Diameter, 3-20ths of an inch. Localities—The deposit in which this Planorbis principally occurs is a transition bed between the upper fluvio-marine and the pure fresh-water formations in Headon Hill. I have also found it, but very sparingly, in the upper fluvio-marine formation at Hordwell, and in the lower fluvio-marine or transition bed which intercalates the upper series of the true marine and the lower fresh-water formations at Mead End. 108 EOCENE MOLLUSCA. No. 61. PLANORBIS BIANGULATUS. F. F. Edwards. Tab. XV, fig. 138 a—d. P. testé parva, compressiusculd, utrinque parum, sed fere equaliter cavatd : anfractibus quinis, singulo antecedentem pauxillulo involventi; supra convexis, ad marginem sinistram angulatis ; subtus convewiusculis, ad marginem externam obscure crenulatis: apertura wre- gulariter obcordata, vie obliqua. A small, somewhat depressed shell, slightly and nearly equally hollowed out on both sides, but rather more so above than beneath. It is formed of four or five volutions, convex on the upper side, and obtusely angulated round the cavity in consequence of the somewhat abrupt inflection of the inner margin toward the preceding volution ; nearly flat on the under side, and obscurely crenulated near the outer margin. The periphery presents two angles; one, rather obscure, near the middle; the other, more prominent, runs round the margin of the lower disc. The aperture is slightly oblique, and of a short heart shape, but irregular in its form, owing to the greater convexity and the angulated inner margin of the upper surface of the whorl. This appears to be a well-marked species; the double angle on the periphery and the crenulated under surface are characters which are not found in any other of the Eocene species. Size.—Diameter, 2-10ths of an inch. Localities—Hordwell, as well in the pure fresh-water, as in the upper fluvio-marine formation; and at Mead End, in the lower fluvio-marine or transition bed before mentioned. No. 62. PLaNnorBIs SowERBYt. Bronn. Tab. XV, fig. 9 a—d. PLANoRBIS SoWERBYI. Bronn. 1838. Letheea geognost., p. 1011, t. xl, fig. 17 a—e. P. testd parva, depressd, utrinque parum et fere equaliter cavata : anfractibus ternis vel quaternis, rapide crescentibus ; supra convewis, infra subplanis, ad peripheriam carinatis, singulo dimidium antecedentis obtegenti, carind inferiori; apertura elongato-cordatd, per-obliqua. The present species appears to be rare. It is a small depressed shell, slightly and nearly equally hollowed out on both surfaces; but the umbilical cavity is the wider and deeper of the two. The volutions are three or four, enlarging rapidly, convex above, nearly flat beneath, and bearing a sharpish keel on the periphery, formed by the compression of the outer margins, a little below the middle of the shell. The whorls are much concealed, each embracing nearly half of the preceding one, and the aperture is very oblique, and of an elongated heart shape. This shell appears to me, as I have already stated, to have been mistaken by M. Bronn for that described by Mr. Sowerby as P. /ens, and to have been correctly PULMONATA. 109 referred to a distinct species. It certainly presents a general resemblance to P. Jens; but the upper side is more arched, the under side flatter, the whorls enlarge more rapidly, and the margins are more compressed and more acutely carinated than in that species; the umbilical cavity, also, is not so deep, and the aperture is of a more oblique and of a more elongated heart shape. In the rapidly increasing size of the whorls and the condition of the marginal keel, the present species presents an analogy with the recent P. exacutus (Gould); but in the latter shell, the upper sides of the whorls are not concealed, the under sides are more convex, the umbilical cavity is deeper, and the aperture is almost obcordate. In P. tropis the shell is more compressed, the whorls enlarge more slowly, and the umbi- lical cavity is wider. Stze.—Diameter, 2-10ths of an inch. Locality.—Sconce. PLANORBIS CYLINDRICUS.—Mr. Sowerby has described a shell under this specific name, (Min. Conch., vol. ii, p. 90, t. 140, fig. 2,) the distinguishing characters of which are the vertically flattened, adpressed volutions, concentrically striated on the under surfaces, and the oblong quadrangular aperture. I have not met with any specimen which presents these characters ; and as the original specimen, unfortunately, has been broken, I cannot give any description or figure of the species. It is not improbable that the shell described by Mr. Sowerby was a fragment, consisting of the early volu- tions of one of the larger species I have described, possibly of P. rofundatus, in which the whorls, in the young state, are somewhat adpressed and the aperture is subquadrate. Genus 14th. ANcyLus.* Geoffroy. AncyLus, Geoffroy, 1767; Miiller, 1774; Draparnaud, 1805; De Roissy, 1805; Férussac, 1819; Lamarck, 1820; Blainville, 1825; Guilding, 1821. PaTsELua (spec.), Linneus, Bruguicre, Montagu. HELcron (spec.), Montfort, 1810. ANsULUS vel ANsyLUs, Gray, 1840. Gen. Char.—Patelliform, thin, obliquely conical, sinistral ; apex rather pointed, compressed, not lengthened nor spiral, turned sidewise towards the right margin and backwards, not marginal: aperture oval or oblong, margins simple. This genus, first withdrawn by Geoffroy from the Patelle, was rejected both by Linnzeus and Bruguiére, but was revived by Draparnaud, and placed near the Limneide, on account of the similarity between the animal and those of Limuea and Planorbis. Férussac, who had noticed the occasional ascent of the animal to the surface of the * Etym. Ay«inos, crooked, twisted. 110 EOCENE MOLLUSCA. water, and assumed that this was for respiration, also placed the genus among the aquatic Pulmonata. On the other hand, Lamarck and Blainville, although they adopted the genus, retained it, provisionally, the former, among the Calyptracea, the latter among the Seutibranchia. Subsequently, the Rev. Mr. Guilding, in his ‘ Zoology of the Caribean Islands,* gave the generic characters of the animal, and described the respiratory apparatus as consisting of a small branchial plume placed on the left side, near the excretory orifice; and M. Deshayes, misled by this description, has, in the 2d edition of Lamarck’s ‘ Histoire Naturelle,’ rejected the supposition of the animal bemg a pulmonated mollusc. The more recent observations of the Rev. G. M. Berkeleyt have shown, however, that the animal, in its organs of respiration, resembles those forming the present order, and that it is, in fact, a true pulmonated mollusc. The respiratory orifice is protected by a valvular enlargement of the margin of the mantle, which, it is conjectured, was mistaken by Mr. Guilding for a branchial plume. The genus, as originally proposed, embraced as well dextral as sinistral species. The dextral species have been withdrawn by Mr. Gray, under the generic name /e/letia, (Acroloxus, Beck;) a division the necessity for which has been questioned, but which, for the reasons stated under the genus Vell/etia, 1 have adopted, and the present genus is therefore confined to the sinistral species. The animal is hermaphrodite, but the union of two individuals is necessary for fecundation: the head is furnished with two cylindrical or triangular retractile ten- tacles, oculated at their bases; the foot is short, and attached to the abdominal mass, and the mantle is large and free, with a simple continuous margin. The living species are not numerous; one only, 4. fluviatilis, is found in this country and in central and southern Europe; the rest occur principally in central America. They live in fresh- water, preferring gentle streams. Four fossil species have been described and referred to this genus, all from the Eocene formations, viz. 4. elegans (Sow.), from Hordwell; 4. depressus (Desh.), from the neighbourhood of Versailles; 4. deperditus (Desmar.), from the fresh-water lime- stone of Ulm; and 4. compressus (Nyst.), from the neighbourhood of Antwerp. The first two are Ve//etig; the descriptions and figures of the last two are insufficient for determining to which genus they belong. No. 63. ANcyLtus? tatus. /. #. Edwards. Tab. XIV, fig. 15 a-d. A. testa conoided, depressa, lata; vertice submediano : apertura oblonga, obovata. The imperfect state of the only specimen I possess, prevents my doing much more than to record the occurrence of this shell, which I refer to the present genus with hesitation. It is distorted at the posterior extremity, and presents the appearance of * © Zoological Journal,’ vol. iii, p. 535. + Ibid., vol. v. PULMONATA. 111 a sinus somewhat resembling that in the shells of the Limacina, but greatly exag- gerated; this, most probably, is due to the accident which produced the distortion, or to some cause similar to that to which Mr. Gray attributes the sinus in Michaud’s A. sinuosus. The shell also is thicker than is usual in this genus ; but the shelly matter has been absorbed and replaced by carbonate of lime, and a slight thickening may have taken place in that process. It may be described as sub-conical, and much depressed, with the vertex about half way between the margin and the middle; the aperture is oblong and widely obovate. Inthe great depression of the shell this species resembles A. (Velletia) depressus, Desh.; but the aperture is more equally rounded at the extremities. Size-—Length about { of an inch; width, about 2-]0ths. Locality.— Sconce. Genus 15th. VELLETIA.* Gray. Acrotoxts, Beck, 1837. Vetietia, Gray, 1840. Gen. Char.—Dextral, with the apex turned sidewise towards the left margin; m all other respects resembling Ancylus. The dextral forms referred to Ancylus were first withdrawn by Beck, under the generic name Acro/oxus, but without any description; the genus was afterwards defined by Mr. Gray under that of Velletia. The animal, so far as its organisation is known, as well as the shell, resembles Ancylus, except that it is dextral and not sinistral ; and the genus has not been received without question, inasmuch as, apparently, it depended on a character insufficient in itself for generic distinction. Mr. W. Thompson, however, in his ‘ Remarks on the dentition of British Pulmonifera,’ to which I have before referred, states that, in their dentition, “dAncylus and Velletia present widely distinct characters, clearly showing that they do not belong to one genus. In Auxcylus there are thirty similar lateral teeth in a straight line on each side of the central tooth, and then there is a slight curve through a series of six more teeth, where a trifling change in their form occurs. In Ve//etia, on the contrary, no part of the horizontal row is straight; its central part is much arched, and is composed of the central tooth and twelve lateral teeth on each side, which do not alter much in form. Then comes one tooth of a different form, and lastly, six more on each side, which latter are in a slight curve.” ll. 12. 13. 14. EOCENE MOLLUSCA. Re Mai SSO &) are Sy Oviform substances of the different sizes found in the fresh-water limestone at Sconce, in the Isle of Wight. An oviform embedded entire, in which the outer covering has been absorbed and replaced by carbonate of lime; the cavity empty. An oviform in a condition similar to No. 11, excepting that the cavity is partly filled with crystals of carbonate of lime. The impression left in the matrix by an oviform embedded entire, the outer covering of which has been absorbed. The internal cast of an oviform of which the outer covering has been absorbed. 123 ORDER—PROSOBRANCHIATA. M. Epwarps. PECTINIBRANCHIATA, Cuvier. TUBULIBRANCHIATA, ” ScUTIBRANCHIATA, oS CYCLOBRANCHIATA, ” PARACEPHALOPHORA DIoIcA, De Blainville. To the free-air-breathing gasteropods succeed those which breathe, by means of gills, the air diffused through the water in which they live. In them the head is more or less fully developed, and the mouth is furnished with a riband-shaped tongue, armed with numerous series of teeth, which present great varieties of form and arrangement. In some cases the animals are hermaphrodite, the sexes being united in the same individual, but in by far the larger proportion the sexes are distinct ; with very few exceptions, they are all oviparous. In the larva state they are always furnished with spiral shells, which, in some cases, as the animals approach maturity, become rudimentary or altogether disappear; but more generally the shells become largely developed, so as to contain the whole animals within them. The respiratory organs exhibit many differences in structure and position,and these varied conditions were adopted by Cuvier as ordinal distinctions in the systematic arrangement proposed by him. De Blaimville, on the other hand, availed himself of the modifications in the repro- ductive apparatus, and divided his second class “‘ paracephalophora,” into the sub-classes dioica, in which the male and female sexual organs are in different individuals, and monoica, in which the two sexes are united in the same individual. To these he added a third division, ermaphrodita, in which he described the generative apparatus as female only, a modification the existence of which subsequent investigation has disproved. It appears, however, by the observations of Milne Edwards, that the water-breathing gasteropods form two natural and well-defined divisions, which that eminent naturalist has called respectively, opisthobranchiata and prosobranchiata, from the position of the gills in relation to the heart.* In the first of these divisions, which corresponds with the zudibranchiata, testibranchiata, and inferobranchiata of Cuvier, and with the monoica and hermaphrodita of De Blainville, the respiration is effected by * Etym. omo(e (in the after part, behind), and zpowsov vel zp@cov (advanced, pushed forward), respectively prefixed to Bpayyia (the gills). 124 EOCENE MOLLUSCA. arborescent or fasciculated gills, which are not enclosed in a special cavity, but are more or less completely exposed, either on the back or on the sides towards the hinder part of the body. The reproductive apparatus is hermaphrodite (not in the sense used by De Blainville, but meaning that the sexes are united in the same individual), and the shell is either wanting or is merely rudimentary in the adult state. In the second division, the abdomen, which is developed proportionately with the cephalic and locomotive masses, is always protected by a shell, generally of sufficient size to contain the whole animal. ‘The mantle forms over the cervical region a vaulted chamber, more or less capacious, in which the branchiz are lodged and the excretory orifices are placed. The reproductive organs, male and female, are borne by different individuals. This division comprises Cuvier’s four remaining orders of the dranchifera, and corresponds with De Blainville’s sub-class dioica. The branchize are composed of simple and par- allel plates, arranged, somewhat like the teeth of a comb, along a vascular stem, and, for the most part, are placed obliquely across the back, or are attached to the right side of the neck. In some genera in this order, the edge of the mantle is prolonged into a canal or siphon, which can be extended at pleasure, so as to permit the free passage of water into the branchial chamber, while the animal itself remains within the shell ; and where this siphon exists, the front of the aperture of the shell presents a notch, or is produced into a channel in which the siphon rests. In other genera the respiratory siphon is altogether wanting, or its place is supplied by a lobe developed from the neck, and in these genera the aperture is without the anterior notch or channel. Sometimes a posterior tube exists with a corresponding notch or canal in the shell; but the function of this posterior tube is simply to provide for the more easy efflux of water or the ejection of the anal excretions from the branchial chamber. The head of the prosobranchiate gasteropod is provided with tentacles, which serve as organs of touch, and probably of smell, and with a proboscis which in some genera is retractile or exsertile. The eyes, with which organs all are endowed, are generally placed either at the bases, or on the extremities, or the sides of the tentacles; but in some genera they are carried on pedicels specially appropriated for them. The presence or absence of the respiratory siphon has been used for the subdivision of the present order into two sections: Ist, Siphonosfomata, corresponding with De Blain- ville’s order siphonobranchiata, and comprising such of the prosobranchiata whose pro- boscis is retractile, and the margin of whose mantle is prolonged into a siphon, and whose shell is, consequently, notched or produced into a channel in front: and 2d, //olostomata, consisting of those in which the proboscis is not retractile, and the animal not being provided with a respiratory siphon, the aperture of the shell is entire. The genera comprised in the first section are all zoophagous, and are inhabitants of the sea or of brackish water; those in the 2d section are, for the most part, phytophagous; the greater number live in salt or brackish water; some, however, are inhabitants of fresh PROSOBRANCHIATA. 125 water. This subdivision, although very convenient, is not, as Mr. Woodward* remarks, altogether satisfactory ; inasmuch as several genera occur among the Aolostomata in which the proboscis is retractile, or the shells are notched or furnished with an anterior canal. By far the greater part of the present order are furnished with an operculum, but many are without that protection. Since Lovén published the result of his examination of the dental apparatus of Mollusca, much attention has been paid to the subject, and great importance is attached to the condition of the lingual teeth. But the assistance derived from this character, however valuable it may prove to malacologists, can be available indirectly only to the paleontologist. Family—Cy PREID&. Genus 20th. Cypraa.t Linn. 1740. Peripoivus, Adanson, 1757; De Blainville, 1825. Cyprma, Lamarck, 1801; De Blainville, 1825. Cyprea, Monftf., 1810. CoccinEeLta, Leach, 1820. Trivia—CyprovuLa—Lvponia, Gray, 1830. Gen. Char.—Shell oviform, oblong or sub-globular, convolute, enamelled, generally smooth, sometimes pustulous, transversely ribbed, or cancellated: spire short, depressed visible only in the young state, when adult, concealed by the enamel; aperture long, narrow, terminating at each extremity in a short canal; outer lip inflected, crenulated ; inner lip crenulated. The animal of Cyprza has a broad, sub-lunate head, terminating in a short retractile muzzle, and bearing long subulate tentacles on bulgings, at the outer bases of which the eyes are placed. The foot is broad, truncated in front, pointed, and sometimes much produced behind; the mantle terminates in a siphon in front, and the lateral margins, as the animal approaches maturity, expand into lobes, generally equal, but frequently more or less unequal, and which can be extended at pleasure, so as entirely or nearly to cover the shell, the edges meeting on the back or on the right side, according as the lobes are equal or unequal. By these lobes is deposited the testaceous matter which forms the enamel-like covering of the shell, characteristic of the family ; the line of juncture being usually indicated, in recent cowries, by a groove or a streak of a fainter colour. The outer surfaces of the lobes are generally covered *