^\2sjeo^\ S^t:.^^^^ ^■^^l(rrjy\^ :}M '' A GUIDE FOSSIL INVERTEBRATES AND PLANTS IN THE DEPARTMENT OF EOLOGY AND PALi^ONTOLOGY BEITISH MUSEUM (NATCEAL HISTOEY), CROMWELL ROAD, LONDON, S.W. WITH 1S2 TLLUSTRATIOXS. PRINTED 13 r ORDER OF THE TRUSTEES. 1897, {All right if I'enfrvpd.) ^ ll 1 >1 Price One Shilling. PRsssi^rrsD OF THE BRITISH MUSEUM, ^7 A GUIDE i )SSIL m VERTEBRATES AXD PLANTS IN THE DEPARTMENT OF iGEOLOGY AND PALiEONTOLOGY BRITISH MUSEUM (NATUEAL HISTOEY), CROMWELL ROAD, LONDON, S.W. PRINTED BY ORDER OF TEE TRUSTEES. 1897. (^All rights reserved.) HRRTFORD : PRINTED BY STKPHKN AUSTIN AND SONS. I B2S TABLE OF CONTENTS. PAGB Table op Contents ......;. iii List of Illustrations . . , . , . . vii Peeface . . . . . . . . . . xiii Table of Stkatified Rocks xiv Introduction ......... xv INVERTEBRATA. Subkingdom I.— MOLLUSCA 1 Class I. — Cephalopoda 6 Order 1. Dibranchiata . , . . ,11 ,, 2. Tetrabranchiata , . . . 17 (a) Nautiloidea . . . .21 (J) Ammonoidea ... 30 Class II. — ^CATKOTODA {Benfalium) . . . .45 Class III. — Amphineura. Polyplacophora (Chiton), etc. 45 / 1 . Opisthobranchiata (including ^,^ ^ \ the Pteropoda) . . . 43 ClassIV.-GASTEROPODA 2.Pul^onata ... 45 ( 3. Prosobranchiata . . .46 Class y.— ^LamiIllibranchiata 45 iv TABLE OP CONTENTS PAOB Subkingdom II. -AHH ULOSA 62 Class I. — Bkachiopoda. . . . 52 Order 1. Atremata . 54 ,, 2. Neotremata . . 54 ,, 3. Frotremata 55 „ 4. Telotremata . . 55 Class II. — Beyozoa (or Poltzoa) 59 Order 1. Trepostomata ,, 2. Cryptostomata „ 3. Cyclostomata . 61 61 . 62 (Division A. — Artheopoda.) 64 Class III.— Teacheata . . 64 Order 1. Insecta (Hexapoda) » „ 2. Myriopoda ...» „ 3. Arachnida f "■ j'^^'"'}^'^- { b. Scorpiomdae . 64 . 67 68 . 69 Class lY. — Ceustacea . 70 Section 1. — Entomosteaca . . 71 Order 1. Ostracoda . . 71 „ 2. Copepoda. [N"one fossil.] „ 3. Phyllopoda ,, 4. Phyllocarida „ 5. Teilobita .... . 72 72 . 72 73 Section 2. — Meeostomata . . > . 77 Order 1. Eurypterida „ 2. Xiphosura . . 78 . 79 Section 3. — Anchoeacephala . 79 Order 1. Cirripedia .... „ 2. Rhizocephala. [None fossil.] . 79 79 Section 4. — Malacosteaca , , , . 79 A. Edeiophthalma , 80 1. Amphipoda . 2. Isopoda 3. Cumacea • • • . 80 80 . 81 TABLE OP CONTENTS. Subkingdom II.— ANNTJLOSA. {Continued.) B. PODOPHTHALMi. 1. Stomatopoda 2. Schizopoda 3. Macroura 4. Brachyura PAOB 81 81 82 83 83 (Division B, — ANABiHaopoDA^) 84 Class V. — Vermes (Worms) , , , . . Group 1 . Turbelleria (flat - worms), [None fossil.] 2. Trematoda (flukes, €tc). [None fossil.] 3. Cestoda (intestinal- worms). [None fossil.] 4. Nemeetini (sea-worms) . 5. Nemathelminia (round - worms). [None fossil,] 6. Ch^topoda (ringed-worms) 7. CJuBtogncdha (arrow- worms). [None fossil.] 8. "QephynsdH (spoon-worms). [None fossil.] 9. Rotatoria ( wheel - animalcules ). [None fossil.] 84 84 85 Snbkingdam HI.— ECHINOBEBHA 88 Class I. HoLOTHUKOiDEA (sea-cucumbcrs) . II. EcHiNoiDEA (sea-urchins) III. AsTEBOiDEA (starfishes) IV. Ophiuboedea (brittle-stars) V. Cbinoidea (stalked sea-lilies) VI. Cystidea (sack-forms) VII. Blastoidea (bud-forms) 90 . 90 95 , 97 98 . 102 102 TABLE OF CONTENTS Suljkingdom IV.— CffiLENTEEA Class I. — Anthozoa . . 1. Alcyonaria 2. Zoantliaria . 3. Ctenophora Class II. — Hydrozoa . 1. Corynida 2. Hydrocorallina 3. Geaptolitoidea 4. Thecaphora Subkingdom v.— POEIFERA . Class. — Spongida (the Sponges) 1. SilicispongiaB 2. Calcispongiae . Subkingdom VI.— PROTOZOA . Class. — Rhizopoda 1. Radiolaeia . 2. fokaminifeea . VEGETABILIA : Fossil Plants Deep- Sea Deposits Historical and Type Collections Stratigeaphical Collections. page 103 104 104 104 104 111 112 112 113 113 113 113 114 122 128 128 128 130 135 140 140 147 Index H9 LIST or ILLUSTEATIONS. PAGE gnette on Title-page, Nautilus simillimus, F. and C. ; Lias, Chaimouth i G. 1. — Univalve shell of iS'ca/arta j3r(?^t<3«a, Lamk. ; Eeceut, China ... 1 2. — ,, ,, Ampullaria canaliculata, Lamk. ; Eecent, S. America 1 3. — Bivalve shell of Glossus (Isocardia) cor, Linn. ; Recent, British 2 4. — Miiltivalve shell of Chiton squamosus, Linn. ; ,, ,, 2 5. — Helix desertorum, Forsk., the desert-snail, with its animal ; Egypt 2 6. — TAraa« jsiAastfo^iwa, Lamk., with its animal; British 3 7. — Nervous system of Taludina or Viviparus, the pond-snail ... 3 8. — Nerve -ganglia and cords of Anodonta, the river -mussel ... ... 3 9. — Part of the radula of Testacella haliotoidea (drawn by S. P. Woodward) 4 10. — Part of the radula of Auricula, sp. (drawn by S. P. Woodward) 4 11. — ,, ,, ,, Siphonaria, sp. ,, ,, ,, 4 12. — Common fresh- water mussel, C'wtojsiC^rMm, Linn. (2 figures) ... 5 13. — ^View of under-side of foot of Zimnaa stagnalis, Linn. ... ... 5 14. — A Pteropod, Cleodora pyramidata, Linn. ... 15. — Sepiola Hondeletii, Gesuer ; Recent, Torbay 16. — Sepia officinalis, lAwa.. 7 17. — Animal of Octopus vulgaris, Lamk. ; Channel Islands 7 18. — Shell of the Pearly Nautilus, Nautilus pompilius, Linn. Indian Ocean 19. — Animal of the Pearly Nautilus in its shell (the shell is cut open) 20. — Mouth, feet, and foot-tentacles of Loligo vulgaris, Lamk. 21. — Suckers of tentacles of Octopus (enlarged)... 22. — Beak, or mandible, of Arehiteuthis monachus, Steen. (one-third nat. size) 23. — Part of the radula of /S^jom q^<;ma/i«, Linn, (magnified) 10 24. — ,, ,, ,, Octopus vulgaris, Lamk. ,, 10 25. — Internal shell and animal of the squid, Loligo media, Linn. British 10 26. — Internal shell or sepiostaire of the cuttle, Sepia officinalis, Linn. British , 10 VIU LIST OP ILLUSTEATIONS, PAGE Fig. 27. — Three figures of animal and shells of Spirula Peronii, Lamk. ; New Zealand 11 ,, 28. — JSelemnoteuthis antigua, Cxmmngton; Oxfordian, "Wilts 12 ,, 29. — Two restorations of animal and shell of Belemnite (after D'Orbigny) 12 ,, 30. — Ammal and sheU. oi Ommastrephes saffiitatus, Lavak. ; British ... 13 ,, 31. — Animal of Belemnite restored (after Owen) 14 ,, 32. — Plesioteuthis (Dorateuthis) Syriaca, H. "W., sp. ; Cretaceous, Lebanon ... ... ... ... ... ... ... ... 14 ,, 33. — Fossil booklets of Cephalopod; Lithographic Stone, Solenhofen 15 ,, 34. — Female Argonaut in act of swimming 16 ,, 35.— («) Female oi Argonauta argo, Linn., contracted into its shell; {b) the shell 15 ,, 36.— Animal and shell of Cheiroteut his Vefanyi, WOrh.; Atlantic ... 16 ,, 37. — ,, ,, Nautilus pompiliut, Linn. ... ... ... 18 ,, 38. — Shell of JVawit^w* (seen in section) 18 ,, 39.— A. Aturia aturi, 'Rasi. ', Miocene, Dax and Bordeaux 19 B. ,, ,, var. Australis, M'Coy ; Miocene, Victoria, Australia 19 ,, 40. — Section of JVaMrcoceras mirum,Ba.TrandiQ; Devonian ,, 28 ,, 61. — Biscites mutabiliSyWQoj; Carboniferous Limestone, Ireland ... 29 ,, 62. — Cmlonautilus mulliearinatus, Shy. ,, „ ,, ... 29 ,, 63. — Solenoeheilus conspicuum, De Kon. ,, ,, ,, ... 30 „ 64. — Goniatites {Glyphioeeras) sphcericus, Martin ; Carboniferous Limestone, Derbyshire 31 ,, 55. — Goniatites (Brancoceras) Ixion, Hall; Goniatite Limestone, Indiana ... ... ... ... ... ... ... ... 31 ,, 66. — Goniatites {Prolecanites) oompressus, Sby. ; Carboniferous Lime- stone, I. of Man 31 I, 67. — Ceratites nodosus, Be B.aaa; Muschelkalk 33 ,, 68. — Trachyceras Aon, Miinst. ; Alpine Trias 33 ,, 69. — Phylloceras heterophyllum, Sby. ; U. Lias, "Whitby 34 LIST OF ILLUSTEATIONS. IX PAOB 60.— Zt/toceras^mhriatum, Shy. ; Middle JAas, Ch&Tmonth. 34 61. — Macroscaphites Ivanii,'D'OTh.; L. CretaceoMS ... 36 62. — ^amt^^s av(ei, Shy. ; L. Lias ... 38 70. — Grammoceras serpentinum, Schloth. ; U. lias ... ... ... 39 71. — Dtsmoceras ligatum, D'Orb. ; Neocomian 39 72. — Stephanocer as Blag deni, Shy.; Inferior Oolite 39 73. — ,, cor onatum, W Oih. ] Callovian 40 74. — Cosmoceras Jason, Heia. ; Callovian, or Oxford Clay 40 75. — Hoplites radiatus, Brug. ; Neocomian 40 76. — Scaphites Huffardianus, D^Orh.; Cretaceous 41 77. — Crioceras Emerici, LeveHie ; Neocomian ... ... ... ... 41 78. — Ancyloceras Matheronianum, D^Orh. ; Neocomian ... ... 42 79a. — Ammonite with aptychus in aperture of shell ; Jurassic ... 42 795. — Aptychus of an Ammonite detached ; Jurassic ... ... ... 42 80. — Vaginella depressa, Bast. ; Miocene, Bordeaux 44 81. — B alantium recurvum, ChUdr. ; Recent, Atlantic 44 82. — Eyalcea tridentata, Gmel. Atlantic and Mediterranean. Miocene: Turin, Sicily, and Dax 44 83. — Conularia quadrisulcata, Sby. ; Coal-measures, Coalbrookdale ... 44 84. — Spondylus spinosus, Shy.', U. Chalk, Gravesend ... ... ... 46 85. — Inoceramus mlcatus, Vark. ; Gault, Folkestone ... 47 86. — Neithea quinquecostat^, Sby. ^ L, Chalk, Lewes, Sussex 47 87. — Pleurotomaria Quoyana, F. and B. ; Recent, "West Indies ... 48 ,88. — ,, platyspira, D'Orb. ; M. Lias, France 48 89. — Eippopodium ponderosum, Sby.; Lias, Gloucestershire 48 90. — Grypheea incurva, Shy.; Lias, Lyme Regis ... ... ... 48 91. — Trigonia costata, Tark. ; Oxfordian, Osmingt on, Dorset ... 49 92. — Valuta Lamberti, Sby, ; Coralline Crag, Gomer, Suffolk (one- eighth natural siie) 93. — Amphidromus (Bulimus) ellipticus, Sby. ; Headon BUU, Isle of Wight (ome-fourth natural size) .. . 94. — Campanile {Cerithium) giganteum, Lamk. ; Eocene, Epemay, France 95. — Atrypa reticularis, JidXman ; Silurian and Devonian 96. — Paterina Labradorica, Billings, sp. ; Cambrian ... 97. — JDiscina circe, 'Bi\\ing& ; Ordovician 98. — Clilambonites Verneuili, Eichw., sp. ; Ordovician ^IC J. 99 >> 100. ,, 101 >> 102. ,, 103 >> 104 >5 105 fi 106 ,, 107. 108 LIST OF ILLUSTRATIONS. PAGB — Camarophoria Schlotheimi, Buch, sp. ; Permian ... ... ... 66 — Lingula anatinafljSimk. ; Recent seas ... ... ... ... 66 — Spirifer striatus, Shy. ; Carboniferous Limestone 57 — Maffellania^avescens, hamk., ST^. ; Recent seas, Australia ... 67 — Diagram of structure of a typical Bryozoan zooid ... ... 60 — Botri/Uopora sociale, 'Nich.. ; Devonian, Canada ... ... ... 61 — SlreblotrypaIIamiltonensis,Wic\i.,ST^.; Devonian, Canada ... 61 — Onychocella Jlabelliformis,'Lamx., s,^.; Bath onian, France ... 63 — Membraniporajurasstca, Greg. ; Bathonian, France ... ... 63 — Wing of Corydalis Brongniarti, Mantell ; Coal-measures, Coalbrookdale, Shropshire ... ... ... ... ... 65 ,, 109. — "Wing of JBrodia priscotincta, Scudder ; Coal-measures, Tipton, Staffordshire 65 ,, 110. — Etoblattina Mazona, ScnMer ; Carboniferous, Illinois, U.S. ... 66 ,, 111. — Names of veins in the wing of a Palaeozoic cockroach (after Scudderj 66 ,, 112. — Progonoblattina Helvetica, Heer, sp. ; Carboniferous rocks, Swit- zerland (after Heer) ... ... ... ... ... ... 66 ,, 113. — Wing of cockroach, Mylacris anthracophilum, Scudder; Car- boniferous, Illinois, U.S 66 ,, 114. — Acantherpestes major, M.. and W.: Coal-measures, Illinois, U.S.A. 67 „ 115. — Euphoberiaferox, Salter;' Coal-measures, Coalbrookdale, Shrop- shire 67 ,, 116. — Eophrynus Prestvieii, H. Woodw., sp. ; Coal-measures, Shropshire 68 ,, 111.— Scorpio of erflAnn.; Recent, Africa (reduced in size) 69 ,, 118. — Palceophoneus, 8Tp.; U. Silurian, Lesmahagow, Lanarkshire ( x x) 69 ,, 119. — Eoscorpius carbonarius, Meek and Worth. ; Carboniferous rocks, Illinois (nat. size) (after Nicholso'n's Palseontology) 69 ,, 120. — Small bivalved forms of Crustacea: Cladocera, Ostracoda, and Copepoda 71 ,, 121. — Entomostracous Crustacea (Phyllocarida and Phyllopoda) ... 73 ,, 122. — Triarthrus BecM, Green; Utica Slate (Ordovician), Rome, New York 74 ,, 123. — Olenellus Callavei, Lapw, ; L. Cambrian, Shropshire ... ... 75 ,, 124. — Paradoxidts Davidis, Salter,- M. Cambrian, St. Davids 75 „ 125. — Agnostus princeps, Salter ; Cambrian, S. Wales 75 ,, 126. — Olenus ; U.Cambrian ... ... ... ... ... ... 75 ,, 127. — Ogygia Buchii, Brong. ; Ordovician, Uandeilo 75 ,, 128, — Calymene Blumenbachii, Brong. ; Wenlock Limestone (SUurian), Dudley 76 „ 129. — Acidaspis mira, Beyr. ; Silurian, Wenlock, Dudley 76 ,, 130. — Staurocephalus Murchisoni, Barr. ; Silurian, Dudley 76 ,, 131. — Somalonotus delphinoeephalus. Green; U. Silurian, Dudley ... 76 ,, 132.— ^ron^cM«/a5e//i/^r, Goldf. ; Devonian, Newton, Devon 76 „ 133. — Brachymetopus Ouralicus, Portl. ; Carboniferous Limestone, Settle, Yorkshire 76 Fig. 134 " 135 >> 136 >> 137 >> 138 >> 139. >> 140 » 141. >j 142 >> 143 >> 144 >> 145 >> 146 J, 147. >» 148 »> 149 >> 160 >> 151 M 152 >> 153 >> 154. f> 155. >> 156 >> 157 „ 158 >> 159 >» 160 >> 161. UST OF ILLUSTRATIONS. XI PAGB ■Griffithides glohiceps, Portl. ; Carboniferous Limestone, Ireland 77 -Phillipsia Eichwaldi var. mucronata, M'Coy ; Carboniferous Limestone Shale, Muirkirk ... ... ... ... ... 77 -Phillipsia Derbiensis, Martin ; Carboniferous Limestone, Derby- shire ... ... ... ... ... ... ... ••• 77 -Fterygotus anfflicus, Ag. (under-side) ; Old Red Sandstone, Forfarshire 77 -Limulus poli/phemus, La,tT. ; Eecent, North America 78 -Falcega Carteri, H. "Woodw. ; Grey Chalk, Dover 80 -^ga monophthaltna, Johnston (living) ; Moray Firth 80 -1, Dromiliies, London Clay ; 2, Pal(eocorystes, Gault ; 3, Eryon, Jurassic ; 4, Mecocheirus, Jurassic ; 5, Cypridea, Wealden ; 6, Loricula, Chalk ... ... ... ... ... ... 81 -CaZ?ia««5«a sMi yjj_ are large and brilliant, and highly developed, resembling those of the higher vertebrate animals. Fig. 23. — Part of the radula of Sepia officinalis, Linn. (Magnified.) Fig. 24.— Part of the radula of Octopus vulgaris, Lamk. (Magnified.) Although the Cephalopoda seem, at first sight, so different from the other members of the molluscan class, they nearly all possess Fig. 25. — [a) Internal shell and {b) animal of the squid, Loligo media, Linn. British coasts. (Reduced.) Fig. 26. — Front and side-view of internal shell, or sepiostaire, of the common cuttle-fish, Sepia officinalis, Linn. British coasts. (Reduced.) a shell (or the rudiments of one) — sometimes external, as in the Pearly Nautilus, Fig. 19, but more frequently internal, as in the squids and cuttle-fishes (Figs. 26 and 27) — which serves to protect the more delicate organs of the body, and corresponds Ce2}halopoda — Dihranch tat a. 11 ■with the external shell commonly met with in all the other Spirula. raollusca; and although it is apparently internal in the squids, CrAMiERY cuttles, and calamaries, it is in reality always enclosed in a sac, or a fold, or lobe of the mantle which secretes the shell. Fig. 27. — Spirula Peronii, Lamk. New Zealand, a, the animal with the shell Table-case in situ ; b, the shell removed from the animal ; c, the shell laid open 67. to show the septa, {a, | nat. size ; b, c, nat. size.) k The nervous system is more concentrated than in the other mollusca, and the larger ganglia are protected by a cartilage. The respiratory organs consist of two or four plume-like gills, placed symmetrically on the sides of the body in a large branchial or ruantle-chamber opening forwards on the underside of the head : in the middle of this opening is placed the siphon or funnel. The sexes are distinct in all living Cephalopods. In Nautilus only, the males are less numerous than the females. The Cephalopoda have been divided into two orders, based upon the number of the gill-plumes present in each ; but they present besides several other important characters by which they can be distinguished and classified. 1. — DiBEANCHiATA (two-gillcd division). Cephalopods having the inflected margins of the mid-foot fused together, so as to form a complete tubular funnel. The lobes of the fore-foot, which surround the mouth, carry suckers disposed in rows. They have in Guide to the Imertebrata. Belem- a single pair of comb-like gills. The oviducts are sometimes __P^ paired (right and left), sometimes only one is developed. A VII. horny or calcareous internal shell is developed in most of them, enclosed in a sac formed by the mantle ; in the Octopoda the shell is not developed, save in Argonauta, the female of which secretes a shell (Fig. 35). The eyes are very highly-developed organs, with a refractive lens, cornea, and eyelids. They are the most striking organs in Fig. 28. — Belemnoteuthis anttqua, Cuunington. Oxfordian : Christian Malford, Wilts. A, booklets on arms ; m, mantle ; other letters as in Fi-. 31. Fig. 29. — Diagrammatic restoration of the animal and shell of Belemnite (after D'Orbigny). these creatures, being both large and brilliant, and well express the keen activity and alertness for which the majority of this wonderful group is conspicuous. All the Dibranchiata secrete an inky fluid, and possess an "ink-bag," having a tough and fibrous structure, with a thin, Cephalopoda — Dibranchtata . 13 silvery, outer coat. It discharges its contents through the anus, ^^^^}^- which opens near the base of the funnel. The inky fluid i GALLERY mulated in this reservoir can be discharged at will by the animal, vil. and serves to cloud the water for yards around, thus concealing its Wall-cases retreat, and so enabling it to evade its pursuers. Many examples ^ * of fossil Dibranchiata are exhibited in the cases, in which the ink- bag is still preserved in siM. la. Fig. 30. -Ommastrephes sagittatus, Lamk. (British), a, the animal ; b, the internal shell or pen. The dried ink-bags of cuttle-fishes and squids are regularly collected and prepared by artists' colourmen to form the pigment known as "sepia." The Chinese and Japanese had probably used it both as a pigment and as a writing fluid long ages before it was known in England ; and it was so used in Greece in the time of Cicero, B.C. 106. From their extreme delicacy, the internal shells of Dibranchiata Cephalopods are but seldom preserved in museums. The solid guards of the Belemnites (Fig. 31) are very abundant in a fossil state. The internal pens of Teuthidse are more rare, but occur in the Cretaceous beds of the Lebanon (Fig. 32) ; in the Lithographic 14 Guide to the Invertehrata. Stone of Solenhofen, Bavaria ; in the Oxford Clay of Wilts ; in the Kimeridge Clay; and in the Lias of Lyme Eegis, and of Boll, See Wall-case 1 and Table-case 59. Cuttle- fishes. GALLERY ■ ^r ^ u yjj m W urtemberg. {a) OcToroDA. — The Octopods (see Fig. 17, p. 7) are characterized by possessing only eight arms furnished with suckers. The section embraces the Argonaut, or ** Paper IN'autilus," and the Octopus, or Fig. 31. — Animal of Belemnite (re- stored by Owen), a, the eight ordinary arms with hooks at- tached ; t, the tentacular arms ; s, the siphon ; o, the eye ; i, the ink-hag ; ph, the phragmocone ; g, the guard. Fig. 32. — Plesioteuthis {Dorateuthis) Si/riaca,'H.W.,sY). Cretaceous: Lebanon. Wall-easel. Showing internal shell and ink - bag near the centre of body. (Nat. size.) "Devil-fish." The Argonaut {Argonauta argo, Linn.), about which many pretty, but fabulous, stories have been told, was the Nautilus primus of Aristotle. The shell is only developed in the female, the male being destitute of any calcareous covering. The Argonaut swims backwards by ejecting water from its funnel, like the cuttle-fishes (Fig. 34). The two supposed ** sails " are the expanded lobes of the pair of displaced and flexed (shell-secreting) arms. The shell is not actually attached to the body, and the animal has Cephalopoda — Dihranchiata. 15 been observed, when injured, to vacate its shell ; neither is the Argonauts shell actually external, being always enveloped, for the greater CrALLERY part, by the lobe-like expansions of the shell-secreting arms (Figs. 35fl!, h). Four species of Argonauta are known ; they all inhabit the Fig. 33.— Fossil booklets of Lithographic Stone: Solenhofen. Fig. 34. — Female Argonaut in act of swimming : the arrow near the funnel (s) shows the direction in which the water is being forcibly expelled from the brancbial chamber ; the arrow behind the shell indicates the direction in which the animal is being propelled. (Reduced.) Fig. 35. — a, Female of Argonauta argo, Linn., when alarmed, contracted into its shell. The expanded dorsal arms still cover more than half the shell. b, Shell of Argonauta with animal removed. (Reduced.) 16 Guide to the Invertelrata. Squids. open water of the warmer seas, such as the Mediterranean, the GALLERY Indian, and China seas. One species, A. hians, Sol., occurs fossil in the Pliocene beds of Piedmont. In the Octopodidae (Fig. 17) the dorsal arms are not expanded as in Argonauta, but are more elongated, and united by a web at the base. The shell is quite rudimentary, but is represented by two short stylets enclosed in the mantle. The body is oval, without fins; the skin is warty and richly covered with pigment-cells; the arms, which are of unequal length, are each provided with Fig. 36. — Cheiroteuthis Veranyi, D'Orb. Atlantic. (Reduced.) a, the animal ; b, a single booklet, enlarged ; c, the internal shell or pen. two rows of suckers (Fig. 21), there being as many as 120 pairs on each arm. The eyes are of moderate size, but the beak is very strong and recurved (Fig. 22). There are six genera living at the present day : of these Octopus is the most cosmopolitan, being found along all the temperate and tropical coasts of the globe. Forty-six living species have been described. A single example occurs fossil in the Cretaceous beds of the Lebanon, named Palceoctopus ( Calais) Newholdi, which has triangular fins on the sides of its body. (h) Decapoda. — From the eight-armed division of the Dibranchiata we pass to the ten-armed "Squids" and ' * Calamaries " (called Cephalopoda — Tetralranchiata. 17 TeutliidcB by Aristotle). This family not only embraces the largest Calama- number of genera, but also those of the greatest size — the giants, ' in fact, of the Molluscan kingdom. They have eight ordinary y^j^ arms and two long tentacular arms, with expanded, club-shaped extremities, which take their origin within the circle of the eight ordinary arms, and are often six times as long. (Fig. 36.) In the genera Sepia, Sepiola, and Rossia these tentacles are retractile, and can be withdrawn into two suborbicular pouches. In Loligo and Sepioteuthis they can be partially drawn in ; in Cheiroteuthis they are non-retractile. These tentacles, which are armed with booklets or suckers at their extremities, are used, like the lasso of the Indian, to seize their prey when at a distance. The fossil booklets of several armed calamaries have been met with in the Liassic and Oolitic formations, and many specimens are exhibited. (See Fig. 33.) Squids and cuttles frequent the sea in numbers, and appear in great shoals at certain seasons (probably for spawning) on the coasts and banks both of Europe and America. They are extremely alert and active in their movements, and, by means of their pigment-cells (called chromatophores), they possess the same power as does Octopus of changing the colour of their skin to suit the surface of the bottom, or rocks on which they rest. Squids are taken in large numbers, for bait, by the fishermen on the coast of Cornwall, with nets or lines. They are called pen-and-ink fish, from the shape of their internal shell resembling a quill pen in form, and from the readiness with which (when alarmed) they discharge the inky fluid contained in their ink-bag. These translucent horny ''pens" increase in number with age, an old squid having as many as three or four enclosed within its mantle, closely fitting together. The eggs are deposited in slender sheaths, arranged in bunches like a mop, as many as 42,000 eggs being found by computation in one bunch. One of the smallest known Cephalopods is the Sepiola Rondeletii. This and an allied species do not exceed two to four inches in length. The body is very short, and has two small, rounded, lateral fins. (See Fig. 15.) 2. — Teteabranchiata (four-gilled division). Cephalopods in which the lateral margins of the mid-foot are inflected (but not fused together), so as to form a funnel by apposition. The lobes of 18 Guide to the Invertehrata. Nautilus the fore foot, which surround the mouth, carry numerous sheathed GALLEEY tentacles (not suckers). There are two pairs of comh-like gills, and two pairs of excretory organs. There are two oviducts, right la, and left, in the female, and two sperm-ducts in the male, the left duct in both being rudimentary. The eyes are hollow chambers opening to the exterior by minute orifices (pin-hole camera) and devoid of refractive structures. There is no ink-sac present in this order. (!See Figs. 18, 19, 37, and 38.) Fig. 37. — Animal and shell of living Nautilus pompilius, Linn. (The shell is cut open to show the deserted hinder chambers.) Fig. 38. — Section of shell of Nautilus showing septa and empty body- chamber. A strong and well-developed external shell, either coiled or straight, is present, and is not enclosed in a fold of the mantle (except perhaps in such narrow-mouthed shells as Gomphoceras, which was probably enclosed in the mantle, as is that of Spirula amongst the Dibranchiata). The shell consists of a series of Nautilida. 19 cliambers, the last-formed of which is occupied by the body of the Aturia. animal, the hinder ones successively deserted, being found, whilst ^'^J'^^^ the animal is alive, to contain gas. A tube, or siphuncle, passes ^^ J^^^ from the body-chamber through each septum of the shell. This la, Table- siphuncle, which in the recent Nautilus is attached to the animal's *^*^® *®- body, is a membranous tube, with a very thin pearly covering. Fig. 39. — Aturia aturi, Bast., from the Miocene (or Oligocene) of Dax, Bordeaux. A, front view of a specimen partly broken open, showing I, I, I, orifices of the lateral lobes of the septa ; s, s, siphuncle. (Reduced f nat. size.) B, side-view of A. aturi var. Australis, M'Coy, from the Miocene of Victoria, Australia, showing the closed umbilicus and the fine lines of growth. (Nat. size.) In the extinct genus Aturia the siphuncle is composed of a succession of funnel-shaped tubes, each inserted into the preceding one (Fig. 39). In others (Pig. 40) the siphuncle is beaded, while in the oldest genera {Actinoceras, Gyroeeras, and Phragmoeeras) the siphuncle is large, and contains in its centre a smaller- tube with radiating plates between, like the lamellae of a coral (Fig. 43). In some instances the siphuncle is preserved and the shell destroyed, giving the appearance of a string of beads {Actinoceras) ; or of a series of vertebrae of some higher animal {Huronia, Fig. 44). Siphuncles of Suronia six feet in length and one and a half inches 20 Guide to the Invertehrata. Nautilus, in diameter were seen by Dr. Bigsby standing out in bold relief GALLEEY from the cliffs of Silurian rock on Drumraond Island, Lake Huron, ^^^* North America, only faint traces of the chambers, in one or two 7 2 8*'*^®^ instances, being visible. In Orthoceras there is evidence of a continued connection through these large and complex siphonal tubes with the whole series of body-chambers ; but if this were the case in the Silurian Cephalo- poda, it is not so in Nautilus^ there being no connection whatever between the siphuncle and the disused and deserted chambers of the shell, which are hermetically sealed up. They are the left- off portions of the cephalopod's habitation, just as much as the lower part of the skeleton of a coral is shut off from the upper part inhabited by the living zoophyte. In EuomphaluSy a Silurian gasteropod, portions of the whorls of the shell, not needed by the animal, are similarly closed by a shelly septum or division. The modern Nautilus is rather a sluggish animal, living mostly at the bottom in deep water, where it may perhaps crawl by means Fig. 40. — Section of Nautilus striatus, Sby., to show the septa and the siphuncle. Lias : Charmouth, Dorset. (Much reduced.) of its tentacles, mouth downwards, feeding upon small crabs and Echinoids. The fishermen of Eiji, the New Hebrides, etc., catch it in their crab-pots, which it enters. Wiley says that it habitually swims backwards, after the manner of other Cephalopods, by discharging the water from its funnel. This Tetrabranch, or four-gilled division, represented to-day by a single living form, the " pearly Nautilus," was formerly most abundant almost all over the globe, shells referred to it being found in rocks of all ages from the Silurian to the newer Tertiary deposits. The extinct genera were extremely varied in form, but nearly all possessed shells of the same compact nature as their Nautilida. 21 modern representative, and most, if not all, of them agreed with it Nautilus, in being external. GALLERY Modifications of the Nautilus type of shell are not unfrequent, and they have given rise to several well-marked groups or genera. ,^J e-cas© Thus, in Barrandeoceras the whorls are few, flattened, and very slightly embracing; in Gyroceras they are numerous, elliptical or subtriangular in section, and very loosely coiled; in Diseites they are also numerous, compressed, and more or less sulcated on the periphery; the umbilicus is wide, and has a central per- foration. In some genera, as Ephippioceras in the Carboniferous, and Aturia in the Eocene and Miocene, the sutures mark the chief differential characters. The septa in the genus Nautilus are generally simple or gently flexuous, but in Aturia they have a deep narrow V-shaped lobe Fio. 41. — Aturia ziczac, Sby., showing the elegant curved lines wMcli mark the septa of the shell. London Clay : Highgate. (Nat. size.) on each side. Some of the Cretaceous and Oolitic species of Nautilus also have very flexuous suture-lines. {a) Nautiloidea. — The fossil forms belonging to this suborder represented in the collection are as follows : — No. of Species. 12. Trocholites, Ordovician. T.-c. 71 13. 6^yro^^rfl5, Silurian, Devonian, Carboniferous, j w ' ' 'j toWM-or r, rr T\ • rr ^, Table-case 2. Ifercoeeras, Devonian. i.-c. 71 6. Barrandeoeeras, Ordovician to Silurian SLndDexoman. ,, 71 10. Diseites, Carboniferous. ji 71 3. Ephippioceras, Carboniferous. ,, 71 14. Coelonautilus, Carboniferous. ,, 71 5. P/^Mro»aw^/Z«*, Devonian, Carboniferous, Triassic. ,, 71 13, Temnocheilus, Devonian to Carboniferous and Trias. ,, 71 9. Solenocheilus, Carboniferous. ,, 71 107. Nautilus, Trias to Recent. T.-c. 59, W.-c. 2 & 13 6. Aturia, Eocene to Miocene. ,, 59, ,, 2 22 Guide to the Invertebrata. VII Wall Ortboceras Althougli the fossil representatives of this section of the ^^^?^^ Cephalopoda (iN'autiloidea) are very numerous and varied in form, they always have simple suture-lines. The simplest form ( OrtJioceras) is like a Nautilus unrolled ; it has a straight, or only slightly bent, more or less conical tube, ornamented some- times with longitudinal, sometimes with transverse ridges, or merely with trans- verse striee, and divided into chambers by transverse partitions. The last chamber is relatively large and contained the animal ; a tube (the siphuncle) extended from the hinder portion of the animal through each partition to the first chamber of the shell, just as in the recent Nautilus. These animals probably crawled along the sea-bottom like the living Nautilus, carrying their shells in a nearly vertical position. This genus, some species of which were several feet in length, ranges from the Cambrian to the Trias, being especially abundant in the Silurian rocks, a very large number having been described from the Silurian rocks of Bohemia. Numerous examples of these straight septate shells may be seen in Wall- case 8, among them being several ex- cellent examples of an Orthoceras from China {Orthoceras Chinense), there known as "Pagoda stones" from the popular belief that they are formed underground where the shadow of a pagoda has fallen upon the surface. Some of these are turn Boll, a example sectioned and polished, and show the Avith some ot the test . , . , ' <. . ,, adherent; i, section with central tube or siphuncle perforating all siphuncle ; c portion of the chambers. A large example of the test enlarged. XJ. Silu- . . _ ^ ^ rian : Gothland. same species may be seen fixed up at the end of the same wall-case. On the wall between this wall- case and the doorway is a fine polished slab from Bohemia, exhibiting numerous examples of these straight-shelled forms. Fig. 42. — Orthoceras orna- Nautiloidea. 23 Among other straight shells may be mentioned JEndoceras^ Actino- Actinoceras, and Huronia. The differences between the two former ... GALLEHY and Orthoceras are illustrated by the fine series of specimens in the ^n glass case mounted on the wall on the left-hand side of the doorway, wall-cases 43«. * 7 & 8. 43*. Fig. 43a. — Fragment of weathered specimen of Actinoceras Bigshyi, Bronn, showing the foramina (/) in the walls of the siphuncle, by which the tubuli thrown out by the endosiphon may have communicated with the septal chambers ; (s) the septa. (Nat. size.) From the Cincinnati Group (Ordovician) : Versailles, Kentucky, U.S. Fig. 43^. — Ideal section (restored) of Actinoceras, showing beaded siphuncle and septa. In Orthoceras the siphuncle is narrow, cylindrical, and usually central or nearly so ; in Actinoceras the portions of the siphuncle between the septa are inflated and bead-like ; while in Endoceras the siphuncle is relatively very large and marginal. Some of the shells of Actinoceras must have been immense, probably ex- ceeding eight feet in length, for in Wall-case 7 may be seen the body-chamber of Actinoceras giganteum, which has a diameter of about 11 inches; and a huge fragment, the whole of which appears to be septate, measures 2 ft. 5 in. in length, the diameter of the larger end being about 8 inches, that of the smaller about 4^ inches. This genus, which possibly occurs in the Cambrian, ranges through the Ordovician, Silurian, and Devonian to the Carboniferous. Huronia resembles Actinoceras, but the portions of the siphuncle between the septa are more inflated in their anterior than in their 24 Guide to the Invertelrata. Huronia. posterior part. This genus, so far as at present known, is limited GALLERY to the Silurian rocks of North America. VII. Wall- case 8. Fig. 44. — Huronia vertebralis, Stokes. Niagara Group (Wenlock) : Druramond Island, Lake Huron. From specimen presented by Dr. Big-sby. The septa are added from Dr. Bigsby's drawing ; they were only indicated in the specimen by "colourless lines on the brown limestone." (Much reduced, after a drawing by Dr. S. P. Woodward.) Wall- case 8. In the genus Piloceras the shell is conical and comparatively short, and the siphuncle very large ; usually only the latter is Fig. 45. — Piloceras invaginatum, Salter. Durness Limestone : Sutherlandshire. S, S, remains of septa ; Si, siphuncle, a little restored in the lower part, with ridges marking the attachment of the septa. (One-half natural size.) preserved. It is found in North America, and in the British Islands only in the Durness Limestone in Sutherlandshire. Nautiloidea. 25 Gomphoceras is sometimes ovoid and nearly straight, sometimes Gomplio- feebly curved : its aperture is very much constricted and more °^^*'' . . • QALL£KY or less T-shaped, and its siphuncle a little inflated between the yjj septa. This genus, according to our present knowledge of it, -v^all- is restricted to the Silurian epoch, numerous examples of both case 7 forms of the genus occurring in the Silurian rocks of Shropshire and Worcestershire. Fig. 46. — Gomphoceras. Silurian : Shropshire, a, nearly straight form [ = Gomphoceras as formerly restricted), b, curved form {= Phragmoceras as formerly restricted), s, s, the siphuncle. case 7. Ascoeeras is a small and somewhat aberrant form. It consists of Ascoceras. two portions, the first, or older, resembling that of an Orthoceras, Wall- having a cylindrical shell, with deep chambers, and a slender, tubular siphuncle, and this stage being succeeded by a second or Ascoceras-stage, after the completion of which the older or Ortho- ceras portion was cast off; hence its rare preservation. In the Ascoceras- stage the shell is sac-like; the septa are fairly regular and close together on one side of the shell, but sweep upwards towards the aperture in a sigmoid curve before they are attached to the other side of the shell. The aperture is simple and open, as in Orthoceras ; but in a closely allied form, Glossoceras, the aperture is partly closed by lobes extending from its margin. Ascoceras occurs in the Ordovician of North America and the Silurian of Europe, by far the greater proportion of the species coming from Bohemia. (See Fig. 47.) Poterioceras ranges from the Ordovician to the Carboniferous. It is a pear-shaped shell, the smaller part being chambered and 26 Guide to the Invertelrata. Ascoceras. perforated by a siphuncle which is somewhat inflated between GALLEKY the septa ; the upper and larger portion contained the animal. The whole shell is usually slightly curved, its aperture being case 7. simple. Yery fine examples of this genus may be seen in Table-case Fig. 47. — A. Schematic view of the interior of Ascoceras manubrium, Lindstr. 57. Upper Ludlow (U. Silurian), I. of Gothland, showing the structure and arrangement of the septa : si, siphuncle ; dt, duct that communicates with the siphuncle of the Nautiloid portion of the shell («, fig. F). B. Schematic view of three sigmoid septa of Ascoceras fistula, Lindstr., seen from the ventral side. C. View of the third septum of the same species, shown as free, as if detached from the shell, to exhibit the large central lacuna. D. The same, viewed laterally (the siphuncular orifice is seen at the bottom of all these figures). E. Longitudinal section of a specimen of Asc. decipiens, Lindstr. , from Sandarfve kulle (hill) , with four regular septa above the sigmoid ones. F. Schematic view of Asc. decipiens, represented as if complete ; n, the Nautiloid portion of the shell. G. Longitudinal and median section of the posterior part of the shell of Choanoceras mtdabile, Lindstr., showing the interior, with the outlines of the incomplete septa ; si, siphuncle. H. Exterior of the same specimen, reduced to about one-third natural size. A model of Ascoceras (executed by Mr. G. C. Crick. F.G.S.) is placed in Table-case 57 at entrance to the Cephalopod Gallery (Gallery VII). Wall-case 7, from the Carboniferous Limestone of Ireland. It must have attained considerable dimensions, for an example of Poteriocerm cordiforme from the Red Sandstone of Closeburn, Dumfriesshire, is nine inches long and seven and a half ipches in its greatest diameter. Nautiloidea. 27 Among these nearly straight forms may also be mentioned the Cyrtoceras. usually short, conical, slightly curved members of the genus GALLERY Cyrtoceras (Fig. 48), which ranges from the Cambrian to the Car- boniferous, the greater number of forms being found in the Silurian, case 7. *m. \ Fig. 48. — Cyrtoceras {Meloceras) clathratum, Foord. Sihirian : Feiiguerolles (Calvados), France, a, part of shell, natural size; b, portion of surface, mairnified. Passing to the forms which are mwe- or less discoidal, we have Lituites, a genus occurring in the Ordovician rocks of North Table- Germany and Sweden, in which the shell is at first coiled in one ^^^^ ' plane, and then extended in a long straight piece until the aper- ture is reached, the latter being contracted by lobes extending Ophidio- ceras. Fig. 49. — Ophidioccras simplex^ Barrande. From tke Silurian of Bohemia. from its margin. Its siphuncle is tubular. Allied to LHuites, but lacking the elongated straight portion, is Ophidioceras (Fig. 49), known only in the Silurian rocks of England and Bohemia. 28 Guide to the Invertelrata, Trocho- ceras. GALLERY VII. Table-case 71. Wall-case 7, Table- case 71. In Trochoceras the shell is not coiled in one plane, but is helicoidal. It ranges from the Cambrian to the Devonian, but attains its greatest development in the Silurian formation, the rocks of this age in Bohemia, England, and the United States containing abundant species. The Ordovician genus Trocholites consists of three or four involute vrhorls, and is coiled in one plane ; it has been found in North America, Europe, and possibly also in India. Gyroceras is coiled in one plane, but the whorls only just touch each other, or are completely out of contact. It ranges from the Silurian to the Carboniferous. Some of the Devonian forms from Germany and South Devon are ornamented with regularly- arranged, strong, tubercular folds ; while some of the Carboniferous forms possessed numerous longitudinal ridges, studded with small tubercles. The discoidal, somewhat evolute shell Hercoceras (Eig. 50 \ is at present known only from the Devonian rocks of Bohemia ; the Fig. 50. — IT^roc^ras mw-wm, Barrande. (After Barrande.) Devonian: Bohemia. Table-case 71. aperture of the shell is partially closed by the infolding of its inner portion ; its whorls are ornamented with a row of spines or strong tubercles arranged longitudinally. Barrandeoceras is a discoidal, involute shell ranging from the Ordovician to the Silurian ; in England it is found in the Silurian rocks of Shropshire and Worcestershire. Biscites, with its compressed, evolute whorls (Eig. 51), is limited to the Carboniferous rocks ; numerous examples of the genus have Nautiloidea. 29 been found in Great Britain and Belgium. There is usually a large Nautilidae. vacuity in the centre of the shell, the innermost portion of the GALLERY shell being sometimes out of contact with the adjacent whorl' ,, ° ** ' Table-case 71. Fig. 51. — Discites nwtabilis, M'Coy. Carboniferous Limestone : Ireland. the inner whorls are often richly ornamented, the older whorls having usually merely transverse lines of growth. Some species Fig. 52. — Coelonautilus multicarinatus, Sby. Carboniferous Limestone: Ireland. have also spiral sulci, but these spiral ornaments are much more prominent in Coelonautilus (Fig. 52), which ranges from the Car- boniferous to the Trias. 30 Guide to the Invertehrata. Nautilidae. Pleuronautilus has strong transverse costae ; it occurs in the GALLERY Devonian, and extends into the Trias. Temnocheilus, ranging from VII . . ' o o the Devonian to the Carhoniferous, has a broad periphery and the 71, prominent lateral portion of the whorl usually angular, and sometimes ornamented with obtuse tubercles. In the Carboniferous genus Solenocheilus (Mg. 53), the shell generally has the form and surface characters of Nautilus proper, the siphuncle is near the periphery, and the lip on each side is drawn out into a narrow spout-like projection. Fig. 53. — Solenocheilus conspicuum, De Koninck. Carboniferous Limestone: Ireland. (Reduced.) Table-case Commencing in the Trias, the genus Nautilus is numerously cases 2 & represented in the Jurassic, Cretaceous, and Tertiary rocks, and 13. about two species are found living at the present day. {h) Ammonoiuea. — Turning from the Nautiloidea to the Ammo- Table-case noidea, we have such forms as Bactrites, Clymenia, and the large group of the Goniatites. In Bactrites the shell is small and straight, the siphuncle marginal, and the sutures simple like those of Orthoceras. In Clymenia the shell is coiled into a flat spiral, the whorls of which are in contact, the siphuncle is large and on the inner side of the shell, and the suture-line is simply folded or lobed. Both genera are found in the Devonian, the former also occurs in the Silurian. I Ammonoidea — Goniatites. 31 The numerous group of the Goniatites is now very much Goniatites subdivided. Its members differ very considerably from each other. GALLERY Some are nearly flat {Beloceras), while others are nearly globular "^W- Table- case 70. Fig. 54. — Goniatite {Glyphioceras Fig. 55. — Goiiiatite [Brancoceras Ixion, sphcericus, Martin). Carboniferous Hall). Goniatite Limestone (Kinderhook Limestone: Derbyshire. Group): Kockford, Indiana. Fig. 56- Goniatite {Frolecanites compressus, Sby.). Carboniferous Limestone: Isle of Man. (Reduced.) (some forms of Glyphioceras). Sometimes the umbilicus is wide, while the inner whorls are more or less exposed; sometimes it is 32 Guide to the Invertehrata. GALLEEY narrow, and the inner whorls are more or less completely concealed "^ ' by the outer whorl. They are usually smooth or with only fine lines ,^Q ' oi growth, rarely with tubercles or ribs. The suture-line may be j^ simply waved [Agoniatites) or angulated {Brancoceras) (Fig. 55), 71, or still more complicated {Beloceras, Prolecanites) (Fig. 56), but it is never foliated and incised as in the Ammonites. The siphuncle is always small and close to the periphery of the shell. Numerous forms of Goniatites are found in the Devonian and Carboniferous, and they also occur in the Permo-Carboniferous rocks of the Salt Eange, India. The great group of the Ammonites (using that term in its general acceptation) is distinguished from all other kinds of chambered shells of the Cephalopod type by the complicated foliations of the margins [sutures) of the partition walls or septa by which such shells are subdivided. Though typically coiled, much in the manner of the flat pond-snail, Planorhis, there are straight and variously curved Ammonites; but all have the common character of a highly foliated ''suture-line." The derivation of the Ammonites from the Goniatites has been clearly made out in certain groups by means of this suture-line, the development of which from its earliest stages of growth has furnished the key in such investigations. The following sixteen families or sections of the Ammonites are the result of recent researches in this large and difficult group of fossils: (1) Aecestid^ ; (2) Tropitid^ ; (3) Ceeati- TiD^ ; (4) Cladiscitid^ ; (5) Pinacoceratid.i; ; (6) Phyllo- CEEATiD^; (7) LYTOCEEATiDiE ; (8) Ptychitii)^ ; (9) Amaltheid^ ; (10) ARiETiDiE ; (11) ^Egoceeatid^ ; (12) Polymoephid^e '; 1 (13) Haepoceratid^ ; (14) Pulchellid^; (15) Haploceeatid^ ; (16) Stephanoceeatidje. 1 These sections will be found amply represented in the Gallery of Cephalopoda, IS'o. VII. J Omitting certain forms of doubtful relationship, to be sub- ^ sequently dealt with, a brief account of the above groups may here be given. The first four families are found chiefly in the Permian rocks of Sicily and of India, and in the Triassic rocks Table-case of the Alps (Alpine Trias). Among the Aecestid^ may be noticed 6^* the singular Triassic genus Arcestes, with its deeply embracing . whorls and contracted aperture ; and among the Teopitid^ the ! characteristic genus Tropites. In the Ceeatitid^ the well-known Ammonoidea — Ammonites. 33 Muschelkalk species, Ceratites nodosus, with its peculiar suture- GALLERY line (Fig. 57), and the richly ornamented shell of Trachyceras Aoti (Fig. 58), are met with. In the Cladiscitid^ may be mentioned gg^ the genus Cladiscites, often ornamented with closely-set spiral ridges. Fig. 57. — Ceratites nodosus, De Haan. Muschelkalk. Three very peculiar shells also deserve notice. They are Chorutoceras, Cochloceras, and Rhahdoceras. In Choristoceras, the last whorl becomes separated from the preceding ones, in the manner of Crioceras. Cochloceras is turreted like a Gasteropod, Fig. 58. — Trachyceras Aon, Miinst. Alpine Trias. and may be compared with Turrilites in this respect. Rhahdoceras is straight, like Baculites. All are from the Alpine Trias. The PusTACOCERATiD^ coutaiu the large species known as Pinaco- Wall- ceras Metternichi, from the Keuper of Hallstadt, in Upper Austria. °**® ^^' 34 Guide to the Invertehrata. 6ALLEBT The extreme delicacy of the ramifications of the sutures in this species excels that of any other Ammonite known. The leaf-like terminations of the sutures in the Phylloceeatid^ are the dis- 11 tinguishing feature in this group ; they are well seen in the typical species, Phylloceras heterophyllum, Fig. 59. This family hegan in the Trias, but it extended through the Jurassic into the Cretaceous. A large example from the Chalk near Brigliton may be seen between Wall-cases 3 and 4, measuring 44 inches in diameter. The suture-line is again the most important feature in the family next in order, viz. the Lytoceratid^, for it supplies the justification for connecting together an assemblage of genera Fig. 59. — Phylloceras heterophi/llum, Shy. Upper Lias : Whitby. Fig. 60. — Lytoceras Jimhriatum, Sby. Middle Lias : Charmouth. Wall- case 11. Wall-case 9, Table- case 61. differing widely in external shape. The family begins in the Trias, and is largely represented in the Jurassic and Cretaceous rocks. One of the most beautiful species of this group is Lytoceras fimhriatum (Fig. 60), whose regular, wavy lines running across the shell make it very attractive to the eye ; the effect being heightened by the bold, sharp, transverse ridges encircling the shell at frequent intervals, representing the former "lips" of the shell. In Macroscaphites the shell is for about four convolutions or whorls exactly similar in shape to a Lytoceras, when it suddenly takes a direction tangential to the coiled part, and after pursuing a nearly straight course for a short distance it bends back in a hook-like termination (Fig. 61). In Hamites the shell is bent at both ends, the apical or smaller (initial) end being again bent : thus the shell has three curvatures. Owing to its slenderness the apical part Ammonoidea — Ammonites. 35 of the shell is rarely obtained (Fig. 62). Samites attains its QAJiXEY greatest development in the Gault. In Hamulina and Ptychoceras (Neocomian and Gault) there is but one sharp bend in the shell, go, Vall^ the straight limbs in Ptychocerm being actually in contact at, and caw 3, in the region of, the aperture. Fig. 61. — Macroscaphites Ivanii, D'Orb. Lower Cretaceous. A still further departure from the typical form of the Cephalopod shell is encountered in the singular genus Turrilites, which takes the form of a Gasteropod shell (Fig. 63). The mouth or aperture is, however, turned towards the left-hand side, or, in other words, the shell is ** sinistral." Turrilites is found exclusively in Cretaceous rocks. Helicoceras is coiled like Turrilites, but the Wall-ease 3 Tablfr- whorls are disconnected. In Heteroceras the last whorl is detached g^g^ gg Fig. 62.— ITamites , D'Orb. Gault: Folkestone. (Fig. 64). Both are Cretaceous genera. In Baculites (Cretaceous) Table- the shell is perfectly straight, except in the earliest or embryonic °*"® stage of its development, in which it is coiled. It occurs in vast numbers in the Danian (Upper Continental Chalk) of the North of France, whence the name Baculite Limestone has been given to those beds (Fig. 65). The next group, Ptychitid^, consists for the most part of Wall-oase Triassic genera, but its earliest representatives come from the cage 89 36 Guide to the Invertehrata, GALLERY Permian rocks of Sicily. PtycJiites and Gymnites, from the Alpine ' Trias, are among the best-known genera. Baraelites of the Permian 69, of Sicily is specially interesting from the fact that its sutural characters resemble those of some of the Goniatites; and taking the Ptychitid^ as a whole it is considered that they present a gradational series connecting the Goniatites with the Ammonites. Fig. —Turrilites catenatus, D'Orb. Gault: Folkestone. Fig. 64. — Seteroceras Emerici, D'Orb. Cretaceous . Table- The principal feature observable in the Amaltheid.e is the heel or projecting edge of the outer border (periphery) of the shell, _^ 68, which is prolonged beyond the margin of the aperture in the form 4, 5, 9-11. of a long narrow process. In Amaltheus margaritatus (Middle Lias) the keel is prominent and beautifully sculptured, resembling Fig. 65. — Baculites anceps, Lamk. Upper Cretaceous. the strands of a miniature rope. Cardioceras cordatum (Oxford Clay) is one of the most highly ornamented of Ammonites, having a series of numerous sharp ribs upon the sides of the shell, which, in passing over the periphery, form a series of fine crenulations (Fig. 66). Schlcenbachia varians (Lower Chalk) has strong and knotted ribs. ■ Ammonoidea — Ammonites^, 37 The family of the Artetid^ embraces a large number of Am- GAILEEY monites which at first sight appear to be only remotely related ; . " nevertheless, a careful study of their development has led to their g 9 n . Tabie- ' cages 62-9. Fio. 66 — Cardioceras cordatum, Sby. Oxford Clay. being grouped together. Among the most familiar members of this large group are the following, viz. : Psiloceras planorbis, which gives its name to the " Eone of Ammonites planorbis^^ of the liower Lias, and at the same time marks the first occurrence of Ammonites in British rocks; Arietites BucTclandi {A. Bucklandi zone) ; Arietites ohtusus, Fig. 67 {A. ohtusus zone) ; and Oxynoticeras oxynolum [A. oxynotus zone). Fig. 67. — Arietites obtusus, Sby. Lower Lias. The shells in this group are flattened in form, and the whorls usually only slightly embracing, and generally numerous (see Fsiloceras planorhis, e.g.). Oxynoticeras oxynotum is remarkable 38 Guide to the Invertehrata. &ALL£BY for the extremely attenuated and trenchant form of the adult ^^^' shell. In this species the whorls are- deeply embracing, so that very little is seen of the inner volutions. Table-ease The ^gocekatid^ are restricted to one genus, uEgoceras, of the ^^2 ^^^®' -^goceras capricornus, Fig. 68 (A. capricornus zone of the Lower Lias), ^. Bavm (Fig. 69), and ^. armatum of the Lower Lias, are some of the most characteristic species. The last-named species is conspicuous for the long spiny processes projecting from the sides of the shell. ISfeil- The family Poltmoephid^ has been constituted to contain certain genera which have been separated from the ^goceratid^ 12. (../' « ^:,^^^^ Fig. 68. — A^ffoceras capricornus, Schloth. Fig. 69. — yEffoceras Davcei, Sby. Lower Lias. Lower Lias. on the one hand and from Haepoceratid^T!; on the other. It is notable for the variations undergone by the shell in passing fiom the young to the adult stage of growth. Liparoceras BecJiei (Middle Lias) is a well-known species with a highly ornate shell. Hammatoceras Sowerhyi (Lower Oolite) has a keeled margin in the young sh&U which it loses in the adult, while the umbilicus, at first narrow^ becomes ultimately wide. Wall- The IIaepo€eeatid^ are derived from the ARiExiniE. The 10*^11 oddest forms begin in the Middle Lias, and they extend into the Inferior Oolite. The shells are flattened and keeled, and have falciform or sickle-shaped ribs, or striae. Hildoceras lifrons, from the Upper Lias of Whitby, shows this kind of ornamentation very distinctly. Leioceras opalinum (Upper Lias) is another characteristic species, the aperture with ear - shaped lateral processes. Grammoceras serpentinum (Fig. 70) characterizes the Ammonoidea — Ammonites, 39 \ *' serpentmus zone," or Jet Ilock, which has yielded some of the GALLERY finest and best preserved Ammonites of the Yorkshire Lias. Of Inferior Oolite species, Ludwigia MurchisoncB and Oppelia suh- jq. radiata may be mentioned. YiQ.IQ.—Grammoceras serpentinum,^c\i\o\^. Fig. Il.—Besmoceras ligattim,WOYh. Upper Lias. Neocomian. The PuLCHELLTD^ (Cretaceous) are remarkable for the simplicity of their suture-line, some resembling Goniatites, others Ceratitcs, in this respect. They are considered to be true Ammonites, descendants of the Jurassic Hakpocekatid^, but in a state of Fig. 72. — Stephanoeeras Blaydeni, Sby. Inferior Oolite. degeneracy. PulchelUa compressisaima (Lower Cretaceous) and Table- Neololites Vihrayeanus (Upper Cretaceous) may be cited as ^*g®* ^^ examples of this small group. The Haploceratidje, ranging from the Inferior Oolite to the Middle Chalk, differ in many respects from the Haepoceratid^, from which they branch off. The shell is generally thick, 40 Guide to the Invertehrata. GALLERY sometimes remarkably so, as in Pachy discus peramplus of the Middle "^^' Chalk ; there are also periodic constrictions or grooves upon ihe surface, which gave rise to the old group-name Ligati. Finally, the contour of the edge or periphery of the shell is uninterrupted, there being no keel such as is met with in the Haepocekatid^. 'J'here is an aptychus in a few forms. Of the flatter kinds of shells of the present family, Desmoceras ligatum (Fig. 71) of the Fig. 73. — Stcphanoceras coronatum, D'Orb. Callovian. «, side-view b, keel view of shell. Table- l^eocomian and Desmoceras planulatum of the Gault, may be case 64. referred to as examples. The last section to be desoribed is that of the Stephanoceratid^, Fig. 74. — Cosmoccras Jason, Rein. Callovian, or Oxford Clay. Fig. 75. — HopUtes radlatus, Brug'. Neocomian. an extensive and varied group of shells which are characterized in many cases by the symmetrical and beautiful ribbing with Ammonoidea. 41 ■whicli they are ornamented. A few examples will serve as illustrations, viz.: Stephanoceras Blag dent {Yi^. 72), Inferior Oolite, Stephanoceras coronatum (Fig. 73) and Costnoceras Jason (Pig. 74), of the Callovian or Oxford Clay, and Hoplites radiatus (Fig. 75), of the Neocomian. Another characteristic shell of this group is the Acanthoceras Rhotomagense of the Lower Chalk. A small group of forms still remains to be considered whose structure (external and internal) has led to their being regarded as offshoots from the Stephanoceuatid^. They may be divided into two sections — the first consisting of shells partly uncoiled ; the second, in which the shells are completely coiled, with deeply embracing whorls. Section I. — The form of Scaphites (Fig. 76) immediately recalls that of Macroscuphiles, but it diff'ers in several particulars : it is GALLERY VII. Wall-cases 5, 9, 10 ; Table - cases 62-8; Table-case 62. Fig. 76. — Scaphites Sugardianus, D'Orb. Fig. 77. — Criocerm Umerici, Leveille. Cretaceous. Neocomian. much more closely coiled, that is, the inner coils of the shell are not seen, being covered up by the succeeding ones ; and further, the uncoiled part is much shorter and its outline more rounded, while it bends over so as to almost reach the coiled part. Table- Scaphites is abundant in the Middle and Upper Cretaceous, case 61. Crioceras has the form and curvature of an Ammonite, but the whorls are not in contact (Fig. 77). It was formerly supposed that this genus was wrongly founded upon broken shells of Ancyloceras {q v.) ; but the discovery of the aperture has dis- pelled this error. There is no doubt, however, that Toxocera& is nothing more than a fragment of Criocerm, Ancyloceras begins 42 Guide to the Invertehrata. GALLERY like Crioceras, but at the last whorl the shell is straightened out at a tangent to the coiled part, and after attaining a con- siderable length in a straight course it bends over abruptly in the direction of the coiled part, as in ScapJiites. Crioceras and Ancyloceras are variously and elegantly ornamented with ribbing, Table- case 63. Fig. 78. — Ancyloceras Matheronianum,WOv\). Neocomian. spines, and tubercles. Crioceras extends from the Neocomian to the Upper Greensand, Aneyloceras (Fig. 78) from the Inferior Oolite to the Chalk. Section II. — This section • includes Ammonites of flat, disc-like form, with Ceratites-\\kQ sutures and deeply embracing whorls. Fig. 79*. — Aptychus of an Ammonite detached. Jurassic. Fig. 79rt. — Ammonite with aptychus in aperture of shell. Jurassic, Sphenodiscus and Buchiceras (Upper Cretaceous) are characteristic genera. Placenticeras (Cretaceous) includes such species as P. Largilliertianum and P. Orhignyanum. Many examples of Aptychi are to be seen in the cases with the Ammonites. The Aptychus is the shelly (or in some cases horny) operculum closing the aperture of the shell in those genera of Mollusca — Pteropoda. 43 Ammonites in whicli the animal could retreat wholly within the GALLERY hody-chamber of its shell. It was secreted by the coalesced pair of dorsal arms, and corresponds with the thick muscular hood which cases 62, closes the mouth of the shell in the living Nautilus. Aptychi 65-68. occur in the Chalk, the Kimeridge Clay, the Solenhofen beds, the Oxford Clay, the Inferior Oolite, and Lias (see Pigs. 79a, h). Ptekopoda, etc. — The Pteropods (" Sea Butterflies " or " Winged Snails ") are found swimming near the surface in the open sea, the living forms being all of small size. They have no distinct head ; the mouth is placed anteriorly in the centre of the forepart of the foot, which is often rudimentary, but may be drawn out into one or more pairs of tentacles and provided with suckers. The lateral parts of the foot are expanded into a pair of wing- like muscular lobes, which are used as paddles. The hind portion of the foot is often rudimentary, but may carry an operculum. The Pteropods are divisible into two sections, the Gymnosomata and the Thecasomata] in both sections the embryo is provided with a shell, but in the Gynmosomata this is soon last and the adult is devoid of any shell, while the adult members of the other section {Thecosomata) generally possess a very delicate external calcareous shell, of which the embryonic shell usually forms the initial portion. In the majority of the Pteropods the shell is symmetrical, but in some {Limaeimdce) it is coiled into a spiral. The Pteropods are all hermaphrodite. They have been heretofore regarded as a distinct class of the Mollusca, but recent investigations show that their internal organization does not essentially differ from that of certain of the Gasteropoda. Indubitable Pteropods are found in the Tertiary deposits,^ but the Mesozoic rocks have not yielded any true Pteropods, and it is not until we come to the Devonian and Silurian strata that forms closely resembling the recent genus Styliola {Creseis) are met with; the Pteropodal nature of these has, however, been disputed. These delicate calcareous shells have a conical form, and no partitions ; they occur in abundance in some of the Devonian rocks of North America. Three important Palaeozoic genera, Tentaculites, SyoUthes, and Table- Conularia, have often been grouped with the Pteropoda. The first ^ The undoubted Tertiary Pteropods have been removed from this case and placed with the other Foreign Mollusca in Wall-cases 1-4 in Gallery VIII. 44 Guide to the Invertehrata. GALLERY has been by some placed in the Annelida ; the systematic position of the whole of these older forms is still, however, uncertain. Table -case 72. See GALLEEY VIII. Wall- case 1. ¥iG. 80. — Vaffinella de- pressa. Bast. Miocene : Bordeaux. Fig. 81. — Balmitium reciirvum, Childr. Recent : Atlantic. Fig. 82. — Hyalma triden- tata, Gmel. Recent : At- lantic and Mediterranean. Miocene : Turin, Sicily, and Dax. GALLERY In Ilyolithes { — Theca) the shell is conical, usually straight, sometimes slightly curved, triangular in section, generally smooth, 72. or with only fine transverse striae ; often provided with an operculum. The species vary in size, being usually an inch or an inch and a half long. They range from the Cambrian through the Ordovician and Silurian to the Devonian, and more rarely occur also in the Carboniferous and Permian rocks. Fig. 83. — Conularia quadrisulcata, Sby. Coal-measures: Coalbrookdale. a, side-view ; b, back ; c, mouth or aperture of shell. The lower extremity is broken off. In Conularia (Fig. 83) the shell is pyramidal in form, tetragonal in section ; each face has a median furrow and is ornamented with transverse smooth or tuberculated ridges, each ridge being angulated in the centre of the face, the apex being directed towards the aperture. The latter is partially closed by an infolded prolongation of each face. The genus occurs in the Ordovician, Silurian, and Devonian, more rarely in the Carboniferous and the Permian formations ; one species has been recorded from the Trias and another from the Lias. Gasteropoda and LamellihrancJiiata. 45 GALLERY YIII. ' II-Y. SCAPHOPODA, AmPHINEUEA, GASTEROPODA, AND Lamellibranchiata. The fossil shells belonging to these groups of Mollusca occupy GALLERY the whole of the west, or left-hand side, of this Gallery. The ^^^PJ- , West Side, foreign specimens are arranged upon the sloping shelves of the --, „ "Wall-cases 1-9, and the British Mollusca occupy the Table- 1-9, Table- cases 89-104. The Gasteropods, or Univalves, are placed first in JJ|®^ ^^^ each case,^ then follow the Lamellibranchs (or Pelecypods) ; the whole series being subordinately arranged in stratigraphical order, commencing with the most recent deposits, such as raised beaches, glacial beds, etc., and going back in time to the Silurian and Cam- brian formations. Those British and foreign specimens which are too large to be placed in either of the tableted series, are mounted on blocks and arranged upon tlie higher shelves at the back of the wall-cases according to their stratigraphical division. All figured and described specimens are indicated by a small green disc. The British Post -Pliocene non- marine mollusca are grouped Table - according to localities and occupy a separate, narrow, upright, ^'^^^ glazed case in the centre of the Gallery, near Table-case 104. These are succeeded by the Pliocene shells of the " ]N^orwich," Table- the ''Red," and the ''Coralline" Crags; under the latter are jq2 j^ io3. arranged the species from St. Erth, Cornwall. Some fine examples of Valuta Lamberti (Fig. 92) are placed in Table-case 102. One of these measures 9^ inches in length ( = 240 mm.); they are from the Coralline Crag of Gomer, Suffolk. In the half of this case are placed the Oligocene Mollusca from the Isle of Wight and Hampshire. Noticeable among these is the Amphidromus {Bulimus) ellipticiis, Sby., from Headon Hill (Pig. 93). Table-cases 100 and 101 contain the Upper, Middle, and Lower Table- Eocene shells from the London and Hampshire basins ; these ^^^^ ^^^' include the Barton, Bracklesham, and London Clay series, etc. Many of the specimens have been figured by Mantell, Sowerby, E. E. Edwards, and others : these all bear a small green disc. A slab of Headon Limestone (Oligocene) almost entirely composed of the shells of one fresh-water snail, the Limncea longiscata^ is fixed in a glazed frame on the wall between Wall-cases 2 and 3. ^ The Scaphopoda [Dentalium) and Polyplacophora {Chiton, etc.), being few in number, are not separated in the cases, but are arranged with the Gasteropods. 46 Guide to the Invertebrata. GALLERY A mass of rock of Lower Eocene age from Fareham, Hants, VIII. "West Side. -^"^^ ^^ ^^^ shells of Pinna affinis, and another from the same Slabs near fo^™^^^o^ ^i^^ shells of Axincea brevirostris, etc., are placed Wall-cases between Wall-cases 4 and 5. Opposite Table-case 98, is a fine slab of " Bognor Rock" from the Lower Eocene of Sussex, largely composed of shells or the casts of shells of Cardita Brongniarti, Axincea hrevirodris, Modiola elegans, Valuta denudata, Pyrula Smithi, Natica Hantoniensis, and Vermetus Bognoriensis. Table- case 99. Ceetaceous Mollusca. — The British Cretaceous series of shells is rich in specimens described by Mantell, S. Woodward, Sowerby, Fig. 84. — Spondyliis spinosus, Sby. Upper Cbalk : Gravesend. Table- case 98. etc. Notice the fine series of Inoceramtis from the Chalk — Table-case 99 and Wall-case 5a. This genus is only met with in the Secondary period. Specimens of Inoceramun Cuvieri measure 18 inches across. Other Chalk species are Spondylus spinosus (Fig. 84) and Neitliea quinquecostata (Fig. 86). There is a beautiful series of silicified shells from the Blackdown beds of Devonshire placed in Table-case 98. The shells from the Gault of Folkestone, from Black Ven, near Lyme Regis, from Okeford Fitzpaine, Dorset, deserve attention; the Scalid^ Gasteropoda and Lamellibranchiata. 47 and Alaeitd^ among the Gasteropods and the NucuI(B and GALLEEY Inocerami (Lamellibranchs) are most interesting. West Side. Fig. 85 — Inoceramus sulcatus, Park. Fig. 86. — Neithea quinquecostata, Sby. Gault : Folkestone. Lower Chalk : Lewes, Sussex. In the next case are the Lower Greensand (Aptian), Urgonian, and ITeocomian Mollusca from Punfield, Atherfield, Tealby, Speeton, etc. Some fine examples of Exogyra sinuata may be Table- seen (one in section shows the great thickness of the shell ^^^^ ' produced by age). Another striking form is the large Pecten cinctiis from the Tealby beds, Lincolnshire ; Cucullcea Gahrielis, from the Atherfield beds, is also of great size. Of the Gasteropods may be named Vicarya Pi%cuetana, Ceratosiphon Fittoni, etc. The fluviatile shells of the Wealden (!N'eocomian) include many examples of the genus Unio, the largest being the Unio valdensis from Sussex and from Brook Point, Isle of Wight. In the centre Table- of the gallery is placed a fine slab of " Petworth Marble," entirely ^*^® ^^• composed of the shells of a fresh-water snail, Viviparus {Paludina) fluviorujn, Sby. The elegant columns of the Temple Church, Fleet Street, are made of this marble from the Weald of Sussex. Jurassic Mollusca. — The British Jurassic shells occupy Table- Table- cases 91-96. Many of them are figured specimens and illus- ^^^\ trate the works of Phillips, Morris and Lycett, Damon, Hudleston, and others. Some of the genera, such as Astarte, Lima, etc., attained a large size when compared with their living representatives. Among the most striking specimens are Pecten lamellosus and Trigonia gihhosa, from the Portland beds ; Astarte Hartwellensis and Pleurotomaria reticulata, from the Kimeiidge Clay ; Bourguetia striata, NerirKza GoodhalU, Trigonia 48 Guide to the Invertvhrata. GALLERY triquetra, Gervillia JBronni, from the Coralline Oolite ; Alaria West side ^^^P^^^^^ ^^^ Pachyrisma grandis, from the Great Oolite ; Pleuro- tomaria (represented by many species), Amherleya Orhignyana, Fig. 87. Pleurotomaria Quoyana, F. & B. Recent : West Indies. Pleurotomaria platyspira, D'Orb. Mid. Lias : France. s marks the position of the slit; the band which encircles the whorls of the shell marks the earlier portion of the slit, now filled up by shell -growth. JSferitopsis Baugieriana, Pinna ampla, Trichites undata, Trigonia, Astarte, and Pholadomya, -of which there are many species, from Fig. 89. — Sippopodium ponderosum, Sby. Lias : Gloucestershire. Fig. 90. — Gryphcea incurva, Sby. Lias : Lyme Regis. the Inferior Oolite^; Grypht^a incurva (T'ig. 90), Oxytoma cygnipes, Sippopodium ponderosum (Fig. 89), Cardinia Listeri, Pleurotomaria anglica, from the Lias. ^ A series of Inferior Oolite Gasteropoda is temporarily arranged in a small table-case in the centre of this Gallery near Table -case 92. Gasteropoda and Lamellilranchiata. 49 Opposite Table-case 94, in the centre of the gallery, is a GALLERY large block of Portland Oolite from the '' lloach-bed," Isle ^"^• of Portland, almost entirely composed of the casts of Trigonia gihhosa, Natica elegans, Cardium dissimile, etc. Fig. 91. — Trigonia costata, Park. Oxfordian: Osmington, Dorset. Between Wall-cases 5 and 6, two slabs of Portland Oolite are fixed on the wall : one contains Perna Bouchardi and Peden lamelloms ; the other is full of the casts of Cerithium concavum. A slab of Kimeridge Clay placed on the wall between Wall- cases 6 and 7 exhibits fine specimens of Ostrea Iceviuscula ; there is also a block, of Coralline Oolite full of specimens of Trigonia clavellata from near Weymouth. In Table-case 91 are placed specimens of Pecten Valoniensis from the Rhaetic of "^^^^ q" Westbury Cliff, and Trochus Waltoni from Beer, Somerset; also impressions of Mollusca from the Upper Keuper of Warwick- shire; and remains of Monotis, Schizodus, Rissoa, etc., from the Permian of Durham. Pal-siozoic Mollusca. — Table-case 90 contains the Carboniferous Table- and Devonian Mollusca ; of the former may be mentioned Anthra- ^^^^ ^• cosia, Carhonicola, Myalina, etc., from Coalbrookdale, figured and described by Sowerby in Prestwich's "Geology of Coalbrookdale." The Gasteropods include JEuomphalus, Leveillia, Bellerophon, etc. The Devonian Mollusca are represented by Anodonta Jukesii and the genus Murchisonia. The Silurian and older Mollusca comprise the genera Euomphalus from the Wenlock Limestone, Table- with its operculum in situ ; Trematonotus, with a central series of perforations; Maclurea from; the Durness Limestone (Ordovician) of Scotland. Prom the Cambrian are forms referred to the genera Glyptarca and PalcBarca, etc. B 50 Guide to the Invertehrata. GALIEBT Key to the Table-cases containing the collection of fossil shells of British Gasteropoda and Zamellihranchiata, including those table-cases arranged in the centre of Gallery. Table -case. 104a. British Post-Tertiary Land and Fresh-water Mollusca. 104. Post-Tertiary (Marine), Pliocene (Norwich Crag). 103a. Pliocene (Norwich, Red, and Coralline Crags). 103. Pliocene (Norwich, Red, and Coralline Crags). 102. Pliocene (Coralline Crag), Oligocene (Hempstead to Headon Beds). 101. Eocene (Upper and Middle). 100. Eocene (Lower). 99. Chalk. 98. Upper Green sand and Gault. 97. Aptian (Lower Greensand), Urgonian, and Neocomian. 96. Wealden (Neocomian), Purbeck, and Portland Beds. 95. Kimeridge Clay and Coralline Oolite. 94. Oxford Clay, Kellaway's Rock, Cornbrash, Eorest Marble, Bradford Clay, and Great Oolite. 93. Great Oolite, Fuller's Earth, and Inferior Oolite. 92. Inferior Oolite. 91. Lias, Trias, and Permian. 90. Carboniferous and Devonian. 89a. Foreign Palaeozoic MoUusca. 89. Silurian, Ordovician, and Cambrian. Foreign Mollusca. — The Foreign Quaternary and Tertiary Wall-cases groups of Mollusca commence in Wall-case 1 with shells from raised beaches like those of Florida and Australia, and with Italian Pliocene shells. Then follow Miocene Mollusca from Bordeaux, from Muddy Creek, Victoria, and from South Australia (Wall-cases 2 and 3) ; next is the magnificent series of Eocene Mollusca from Paris, Grignon, and Epernay. The shells of the Paris Basin exhibit strong affinity with those of the English Eocene ; but the former are often more perfectly preserved and the species more abundant than in the latter deposits. Fine specimens of Campanile ( Cerithium) giganteum (Fig. 94) from Grignon are placed in a glass case between Wall-cases 3 and 4, and others are mounted in the wall-case, together with a longitudinal section showing the shelly plaits upon the columella. In a glass case, between Wall -cases 2 and 3, is exhibited the shell of Gasteropoda and Lamellihranchiata. 51 a great Cyprcea {C. gigas), from the Murray River (Miocene) beds GALLERY of Australia, which greatly exceeds in size the living Cyprcea cervus from the Pacific, regarded as the largest living species. 5 & e. The foreign Cretaceous shells occupy Wall-cases 5 and 6. There is exhibited here a fine series of Radiolites {Ilippurites)^ shells allied to the existing Chama, which probably lived in clusters adhering to coral-reefs in the Cretaceous sea. They are rare in this country, but the ''Hippurite limestone " is well developed in France, Spain, and Fig. 92.~ Foluta Lam- berti, Sby. Coralline Crag: Gomer, Suffolk. (Reduced to \ nat. size.) Fig. 93, — Amphidromus ( Bulimus ) ellipticus, Sby. Headon Hill, Isle of Wight. (Reduced to \ nat. size.) Fig. 94. — Campanile {Ceri'hium) gigan- teum, Lamk. Eo- cene : Epernay, France. (Reduced to -oV nat. size.) Italy, and it often occurs in the East and West Indies, etc. On the wall are exhibited specimens of Inoceramus expansus from Cretaceous beds in Natal, South Africa. In the wall-case are placed shells of Alectryonia ungulata, Neithea quadricostata, Pinna cretacea ; large Nerincea from Spain ; with Cucullcea, Inoceramus, Gervillia, Trigonia, etc. Numerous beautiful examples of Trigonice are here exhibited, ranging from the Lower Lias to species living at the present day off the coast of Australia. The next case (No. 7) contains the series of foreign Oolitic Wall- shells. There is a fine series (part of the Tesson Collection) ***^® from the Lower Oolite of Normandy, agreeing closely with those from British localities of a similar age. Amongst the Gasteropods are Trochus, Neritopsis, Amherhya, Nerita, Pleurotomaria, etc., the bivalves being represented by Astarte, Trapezium, Opis, Trigonia, Pholadomya, Ceromya, etc. The succeeding wall-cases (Nos. 8 and 9) contain the Mollusca Wall-cases from the Lias and Trias, followed by the Palaeozoic Beries, Permian " * *• to Silurian. Lithotrochus Sumholdti, from the Lias of South America, and Trigonia navis, from Germany, may be referred to. 52 Guide to the Invertelrata. 6ALLEB7 Attention is also called to the series of Mollusca from the Trias VIII WestSide. ^^ ^^' ^^ssian (collected by Klipstein), of which Myophoria is Wall-cases ^ prominent genus, related to Trigonia in some of its characters. 8&9. The Permian shells are chiefly from Gera, Germany, and include Schizodus, Pleurophorus, Pleurotomaria, Chitonellus, etc. The Permo-Carboniferous series is represented by specimens from Australia of the genera Platyschisma, Pachydomus, Mirydesma, Orihonota, Conocardium, etc. ; several of these are types figured in Strzelecki's Memoir, 1845. The Carboniferous of Belgium is represented by the genera PJuomphalus, Loxonema, Chiton, Cono- cardium, Pinna, etc. ; the Devonian of Germany by Murchisonia , a banded shell related to Pleurotomaria, and by Megalodon cucullatus. The Silurian genera from Bohemia exhibited are Tulina, Capulus, Polytremaria, Conocardium, etc., part of the Barrande Collection. There is a small table -case in the centre of the gallery, placed near to Table - case 89, containing a series of foreign Palaeozoic Gasteropods belonging to the families Bellerophontidjb, Pleukotomariidje, and Solaeiid^. GALLEEY II.-ANNULOSA. vni. East Side. I.— BRACHIOPODA. Wall-cases 10 & II, The Brachiopoda are animals that live in the sea, and have Table- cases ^ ^oft body enclosed in an external shell with two valves. They thus look something like bivalve Mollusca ; but both the Fig. 95. — Atrypa reticularis, Dalman. Silurian and Devonian. a, dorsal or peduncular valve ; b, ventral or brachial valve. Shows bilateral symmetry, and slightly greater size of dorsal valve. shell and the soft parts have really a very different structure from those of the Mollusca. So much of the anatomy of the Brachiopoda as is important to the student of fossils, is illustrated by the large lO&lI. coloured diagrams in Wall-cases 10 and 11. The two valves of the shell lie on the back and front of the animal, not on its sides as in bivalve molluscs. Each valve is symmetrical Brachopoda. 63 in itself, its right and left halves resembling one another. On CrALtEEY the other hand, one valve is nearly always larger than the other j.gjj|. gj^^ (Fig. 95«). By the larger valve the adult animal is usually wall-casea attached to rocks or other objects. In a few forms, such as 10 & 11, Crania (Diagram 1), the valve is directly cemented to the rock by its own substance. In others, such as Lingula (Diagram 2 86-b8. and Fig. 100), the valve is attached by a long muscular stalk, the "peduncle" or "pedicle," which is capable of waving movement and of contraction. There are also intermediate stages, with shorter peduncles, such as Semithyris (Diagram 8) and Bucina (Fig. 97). This larger, attached valve is therefore often called the "peduncle valve": by English writers it is called the "ventral valve," although in the natural position of stalked forms it is always the uppermost. Similarly the smaller valve is called the "dorsal valve"; but a better name is "brachial valve," which reminds one that this valve often bears a calcareous skeleton supporting the so-called " arms " (Diagram 9 and Figs. 101 and 102). In microscopic structure also the shell differs from that of the Mollusca (Diagram 3). It is mainly composed of small prisms of calcite (carbonate of lime), which usually lie at right angles to the surface of the shell. In the harder-shelled forms these make up the greater part of the shell, merely being coated on the surface with a layer of slightly different texture and with a thin horny membrane, the " periostracum. " In the softer- shelled forms, such as Lingula, horny substance occurs not merely on the surface, but in layers between the prisms, which in this case are of phosphate of lime. In many genera, such as Terebratella, Crania, Cistella, the shell is perforated by a number of small canals ; these contain processes of the mantle, the arrangement of which is shown in Diagram 2>a. In fossils this structure gives to the exterior of the shell a pitted or " punctate " appearance under a magnifying glass, and thus enables one to distinguish such shells from those which are "impunctate," as the shells of Atrypidae and most Khynchonellidae. In those Brachiopoda that appear to be the simplest and oldest, the shells are not as a rule joined by any hinge (Diagram 7). These have therefore been called Inaeticulata or Ecaedines * : they include Lingula, Bisana, Oholus, Crania, Trimerella, and their allies. In more advanced forms, such as Orthis, Leptcsna, Atrypa, ^ £, without ; cardo, a hinge. 54 Guide to the Invertelrata. frAlLEBT Terehratula, a hinge is developed at the hinder end of the shell East Side (I^'agram 4). These have therefore been called Articulata or Wjftll-casea Testicardines.^ As classificatory divisions, however, these are not ^^w ^^* altogether satisfactory, for the Articulata are necessarily derived eaaea horn the Inarticulata, and intermediate forms are not rare. §a-«8. In the relations of the peduncle to the valves one can trace a gradual evolution. The simplest type is seen in Paterina (from the Cambrian, Fig. 96) and Lingula (Cambrian to present day, Fig. 100), Fig. 96. — Paterina Labradorica, Billings, sp. Cambrian, An example of the Atremata^ aud the simplest known form of BracMopod shell. where the peduncle simply passes out betvreen the valves and is not enclosed by either of them ; there is therefore no hole, or trema irprjiitq)^ through vt^hich the. peduncle may pass, and such genera constitute the order Atremata. In Trematis, Discina (Fig. 97), tSiphonatreta, and their relatives (mostly Ordovician and Silurian), the peduncle is restricted to the ventral valve ; it lies in a groove or Fia. 97. — Discina ciree, Billings. Ordovician. An example of the Neotremata. The peduncular valve, showing the delthyrium, which has become surrounded by the valve, and is also partly filled in from underneath by a shelly deposit. fissure (" delthyrium "), which remains open in primitive forms, but closes round the peduncle (forming a rprj/^a) in later forms : such genera constitute the order Neotremata. Kext, the fissure or "delthyrium" in which the peduncle lies, assumes a triangular shape ; the peduncle lies towards the apex of the triangle, and itself secretes a single shelly plate ("pseudo-deltidium "), which ^ Testa, a shell ; caido, a hinge. Brachiopoda. 55 gradually fills up the triangular fissure till only a small foramen GALLERY is left at its apex, as in Clitamhonites (I'ig. 98) and Rafinesquina ^^^^ g/^^ (Diagram 4) ; later in life the pseudo-deltidium may be reabsorbed, wall-cases 10 & 11, Table- cases 86-88. Fig. 98. — Clitambonites Verneuili, Eichw,, sp. Ordovician. A.U example of the Protremata. The shell is seen from the side of the brachial valve, above which is the lofty hinge-area of the peduncle valve. The delthyrium is covered by a single pseudo-deltidiura, through which the peduncle passed by the foramen (K). as in the Orthidae : such genera constitute the order Proteemata. Some forms have taken another line of evolution : in them the pseudo-deltidium is either absent or soon reabsorbed, so that the delthyrium is open in early life, but at a later period it becomes partly or entirely closed by tv?o **deltidial plates," which are secreted by the edges of the mantle along the sides of the delthyrium, and which may subsequently meet either above or below the peduncle, and may even fuse into one plate, the * * deltidium " ; these plates are well seen in Alrypa (Fig. 95) and String ocephalus, and occur in Rhynchonella, Spirifer (Fig. lol), Terehratula, and allied forms : such genera constitute the order Telotkemata. The orders Atremata and Neotremata are equivalent to suc- cessive stages of the Inarticulata, and are most abundant in the earlier Palaeozoic rocks. From them the Protremata and Telo- tremata arise as divergent groups, which together are the equivalent of the Articulata, The Protremata were dominant in later Palaeozoic time ; the Telotremata in Mesozoic. The shell-valves are secreted by the two mantle-folds which line them. These are extensions of the body- walls, and they contain prolongations of the body-cavity, in which is a blood-like fluid and in which the generative products are formed. These vessels often produce impressions on the inside of the shell, and 60 can be traced in the fossils, e.g. Camarophoria (Fig. 99) and a fine specimen of Orthis [Schizophoria) striatula in the wall-case. 66 Guide to the Invertehrata. GALLERY The outer edges of the mantle-folds are set with bristles ('' East Side These structures are shown in Diagrams 5 and 11. Wall-cases lO&ll, Table, cases Fig. 99. — Camarophoria Schlotheimi, Buch, sp. Permian. Ventral side of internal cast, showing the impressions of vessels in the mantle-fold. Muscles pass across the body of the animal from one shell-valve to the other (Diagram 6) ; they serve to open and to close the valves, and to move them sideways. The attachment of these muscles to the shell forms scars, and in fossil Brachiopods these scars are the only evidence we have as to the arrangement of the V D Fig 100. — Lingula anatina, Lamk. Recent seas. Interior of V, ventral or peduncular valve, and D, dorsal or brachial valve, to show muscle-scars, which are denoted thus : «. urabonal ; p.s. parietal ; tm. transmedian ; e.-l. externo-lateral ; m.-l. medio -lateral ; c. central; a. -I. antero -lateral. muscles. It is therefore important to understand the meaning of these scars; and to help the student, a very careful drawing from life of the inner surface of a Lingula shell has been made (Diagram 7 and Fig. 100), which may be compared with the adjacent diagram showing the muscles. Brachiopoda, 57 The viscera lie near the hinder or peduncular end of the shell, GALLERY and the mouth is directed towards the forepart or opening of j-^gt side. Wall-cases 10 & 11, Table- 86-88. Fig. 101. — Spirifer siriatus, Sby. Carboniferous Limestone. An example of tbe spire-bearing Telotremata. The sbell is seen from the side of the brachial valve, and portions of that valve are broken away, exposing the spires that support the arms of the lopho- phore. Between the umbones of the peduncular and brachial valves is seen the delthyrium, partly filled in by the deltidial plates that have met and fmed above the foramen into a single deltidiura. Fig. 102. — Magellania Jlavescens, Lami,, sp. Recent seas, Australia. An example of the loop -bearing Telotremata. A. — Interior of peduncle valve. /, foramen for peduncle, below which are seen the two deltidial plates ; t, teeth of hinge ; a, b, c, muscle -scars ; b', scar of peduncular attachment. B. — Interior of brachial valve, c, c', cardinal process for attachment of muscles ; b, hinge-plate, supporting cardinal process and prolonged below into p, the median septum ; s, sockets for the teeth of the peduncle valve ; /, loop, supporting lophophore ; a, muscle-scars. the shell. The mouth is surrounded hy a somewhat horseshoe- shaped disc ; this bears tentacles that are furnished with minute, rapidly-moving processes known as "cilia," which drive towards 58 Guide to the Invertehrata. GALLERY the mouth currents of water containing food-particles ; it is called East Side, the " lophophore " (tuft-bearer), and resembles the structure of Wall-cases the same name in the Bryozoa (Diagram 8). This lophophore T^w ^^' ^^ often produced into two processes, which fill the forepart cases and sides of the shell-cavity and are often spirally coiled. These 86-88. processes are generally known as '* arms," and, since they were formerly supposed to represent the "foot" of the Mollusca, their presence suggested the name BfiAcniopoDA {^paxii^v, an arm ; and TToi's, a foot). The arms are often supported by a calcareous skeleton, the shape of which is of great importance in classifying fossil Brachiopods. Thus, the Telotremata branched into loop- bearing forms (Diagram 9 and Fig. 102, Magellania) and spire- bearing forms (Diagram 9, Atrypa^ and Fig. 101, Spirifer). The mouth leads to a slightly coiled intestine (Diagram 10), which in the Inarticulata is provided with an anus (whence this class has also had the name Tretenterata ' applied to it). It seems that some of the earlier Protremata were also provided with an anus ; but in the later Articulata this structure became degenerate, and no longer exists in the living representatives of the class ; for them, therefore, the name Clistenterata * was proposed. The Brachiopoda possess a system of blood-vessels with a con- tractile heart, a distinct nervous. system, and a pair of excretory organs (''nephridia "), which serve also for the transmission of the generative products (Diagram 11). The sexes are usually separate. The Brachiopoda are found in seas all over the world, and usually at depths of less than 100 fathoms, but they have been dredged at a depth of 2,900 fathoms. Most attach themselves permanently to a hard bottom by the peduncle, open their shell so far as the hinge permits, and collect miimte food-particles in the currents of water that flow down the lophophore. Some protrude and even unroll the arms. Lingula, as shown in Diagram 2, lives in a tube in the sand, forming a case of agglutinated sand around the lower end of its peduncle; it stretches its shell to the opening of the tube, and the projecting setae guide the currents of water down to the lophophore; but ^ Meaning "pierced guts.' ' Meaning "closed guts." Brachiopoda and Bryo%oa. 59 when disturbed, the peduncle contracts and the shell is withdrawn GALLERY into the tube, which closes in above. It is not, however, to be j-^g^ g^'^g inferred that all extinct species of Lingula and of similar genera -wall-cases lived in this way. 10 ^ 11» . . Table- Though Brachiopods usually occur in great numbers wherever cases found, they are not so numerous now as they were in past ages. 86-88. In the Carboniferous period especially, the number of species and individuals was very great, and the Producti then living reached a larger size than any Brachiopod before or since. Specimens may be seen on the upper shelves of Wall-case 10. Terehratula grandis, of the Coralline Crag, is the largest Brachiopod found in later rocks. In this Gallery the British fossil Brachiopoda are arranged in Table-cases 86-88, in stratigraphical order. The important _ . British specimens, forming the types of Davidson's great mono- cases graph, are, however, exhibited in Gallery XI. Here are also placed 8&-88. the numerous type-specimens of Sowerby. The Davidson Col- lection contains many Brachiopoda from foreign localities, which are of great interest either as types or as showing structural characters. The general collection of foreign fossil Brachiopoda is placed in Wall-cases 10 and 11 of Gallery VIII. Among them Wall-cases the specimens of chief interest are those from the Palaeozoic rocks * of the Arctic regions and from Australasia. II.— BRYOZOA.' The Bryozoa are animals, including the Sea Mats, which live in either fresb or salt water, mostly in the latter. With one exception {Loxosoma), they always live in colonies, which are generally fixed. A colony consists of a large number of individuals (or zooids), each of which is completely separated from the rest and enclosed in a double-walled sac. The digestive tube is U-shaped, the mouth and anus being placed close together. A band of tentacles occurs around the mouth in most forms, but in one group (Entoprocta) this surrounds both the mouth and the anus. Unlike the Mollusca, to which the Bryozoa were once regarded as akin, they have only one nerve -ganglion. * The name Polyzoa has been adopted for this class by many English authors. 60 Guide to the Invertelrata. Bryozoa. GALLERY VIII. Centre- cases 86a & 86b, Wall-case 12a. Bryozoa are frequently found upon the seashore, either spreading in delicate gauze-like sheets over weeds, shells, and stones, rising in hard shrub - like tufts, forming hemispherical masses, or spreading in flexible horny branches. Owing to their mode of growth, they are generally mistaken for seaweeds. The classifi- cation of the Bryozoa depends upon the structure of the small "zooids," and the microscope is indispensable in their study. In the arrangement of the collection, therefore, specimens are exhibited to show the general form and "habit" of the colony, and drawings are placed beside them to show the minute structure of the zooids. The specimens are in most cases sufficiently near Tm Fig. 103. — Diagram of structure of a typical Bryozoan zooid. an. anus; ap. aperture ; b.c. body-cavity ; c.p. communication pore ; d. diaphragm ; ect. ectoderm ; end. endoderm ; /. funicidi ; n. nerve-ganglion ; o. orifice ; oes. oesophagus ; op. operculum ; r.m. retractor muscle ; st. stomach ; T. tentacles ; t.s tentacle sheath. Wall case 12a. to the front of the case to admit of the use of a magnifying glass, and thus the main features of the zooids can be recognized. Some of the colonies too large to be included in the table- cases are placed in Wall-case 12a. Most of the living Bryozoa are soft-bodied animals, and only two, or possibly three, of the existing orders are represented in the fossil faunas. There are two other orders (the Trepostomata and Cryptostomata), which are now extinct. The fossils, however, all belong to the Gymnolaemata, one of the three main divisions of the Bryozoa. The Bryozoa are abundant fossils in many formations, and Bryo%oa, 61 therefore, though the exhibition series of British species is fairly complete, only a few representatives of the foreign forms are exhibited. The main series of British Bryozoa are exhibited in two high tables in the centre of the gallery. Specimens too large for this series, and the foreign forms, are in Wall-case 12a. Commencing with the central table-cases, we find in the first place a series of specimens from the Ordovician rocks of Wales. These are in an unsatisfactory condition of preservation, and they can only be determined by the assistance of better specimens yielded by rocks of the same age in America. One species is referred to the existing genus Berenicea, but the rest belong to two extinct orders — the Trepostomata and Cryptostomata. In the Silurian deposits the Bryozoa are in more perfect con- dition, and the specimens from the Wenlock Limestone include some interesting and elegant forms, such as Ptilodictya suhlanceo- lata, Penniretepora Lonsdalei, and several species of Fenestella and Polypora. Bryozoa. GALLERY VIII. Centre - 86a & 86b, Wall -case 12a. Fig. 104. — Botryllopora sociale, Nicli. Devonian : Canada. a, portion of HeUophyllum with a small group of discs of Botryllopora adherent to it (nat. size), b, a single disc en- larged ; 0, one of the radiating ridges enlarged to show the cells. Fig. 105. — Streblotrypa Hamil- ^o«(?«sis, Nich.,sp. Devonian: Canada. a, nat. size, and b, enlarged, to show the cells and the tubular intercellular interspaces. The Devonian fauna is small, and the specimens are not well preserved ; the type-specimen of Fenestella prisca (Phil.) is the best in the series. The Carboniferous Bryozoa, on the other hand, are numerous and in good condition. The most important genus is Fenestella-, the size to which colonies of this attain is shown by two specimens mounted on blocks in Wall-case 12a. The Wall-case fan-shaped species of this genus and of Ptilopora, the feather- ^ * shaped Penniretepora, and the cylindrical Rhomhopora, are the most interesting forms in the table-case. Hemitrypa should not be overlooked, as it consists of a colony formed of two layers, of 62 Guide to the Invertehrata. Bryozoa. which the upper was once regarded as a coral growing as a parasite GALLERY on a Fenestella. VIII. The Permian species are few in number, and the five chief cases species are illustrated by a representative series. Three specimens 86a & 86b, too large for the table-case are placed in Wall-case 12a. 12a. The next fauna represented in England is that of the Jurassic system, which shows a great advance from that of the Palaeozoic ; old types such as Fenestella^ Penniretepora, Acanthocladia disappear, and species belonging to existing genera form the largest part of the fauna. Among these, Stomatopora, Berenicea, and Diastopora are the most important, and are illustrated by an extensive series of specimens. These are associated with forms such as Ceriopora^ which are survivals of the Palaeozoic group of Trepostomata, and others such as Theonoa and Apsendesia, which are typically Mesozoic. The ensuing Cretaceous fauna in many ways resembles the Jurassic. Trepostomata survive, and the Cyclostomata are still in the ascendancy. Examination, however, of the specimens ex- hibited, shows that the Cheilostomata are now fairly abundant, as we may see by the numerous species of Memhranipora and Onychocella, and the presence of more specialized genera such as Crihrilina. Passing to the Eocene, we find that the fauna in England becomes much smaller, though that of the Mediterranean Basin at the same period was very large. The forms, moreover, are scarce and dwarfed, as they lived in a sea exposed to the north and cut off from the warm waters of the Mediterranean by a land barrier across Central France and Germany. Hence genera such as Idmonea are represented only by small delicate colonies (see e.g. Idmonea coronopus, from the Paris Basin), which are in striking contrast to the massive growths found in Italy and Austria. The fauna is therefore aberrant, and includes a remarkably high percentage of peculiar species. Among these, Orhitulipora petiolus, consisting of a disc supported on a short stem (see e.g. specimen, B. 4349), Adeonellopsis JVetherellt, and JVotamta Wetherelli, are the most interesting species; Schi%oporella magnoaperta, Smithia tulularis, and EntalopJiora tergemina, are of interest as representing modern types of existing genera. The Pliocene in England is much richer than the Eocene, and comparison need only be made between the small fragile specimens Bryo%oa. 63 from the latter with such massive colonies as those from the Crags, which owing to their size have to he placed in the wall-case (No. 12a), to realize that the Bryozoa were then living under more favourable conditions. In fact, the Arctic Ocean was probably cut off by a land barrier to the north, while there must have been free communication with the seas to the south. The collection in the Museum from this period contains the specimens used by Busk as the types of his monograph on the ** Crag Polyzoa." The most interesting forms found in the Crag are some massive Cyclostomata, including the three species known as Alveolaria semiovata, Fascicularia aurantium, and F. tuhipora. Among the Cheilostomata, the most remarkable forms are two species of Cellaria (syn. Salicornaria) and one of Melicerita. The numerous species of SchizoporellUy Mucronella, and Memhranipora are closely allied to or identical with living forms. Bryozoa. GALLERY VIII. Centre - cases 86a & 86b, Wall-case 12a. Fig. 106. — Omjchocella Jiahelli- Fig. 107- — Membranipora jurassica, Gire^. /or??zis, Lamx., sp. Bathonian: Bathonian : France. France. A small collection of Pleistocene species from the Clyde and from Nelsea Bill is exhibited; but all these species still live on the English Coast. The foreign Bryozoa are exhibited in Wall- case 12a; but the Wall- case collection is not yet arranged, and only a few representative species are exhibited. The lowest slope is devoted to the Palaeozoic faunas, chief of which is that from the Silurian rocks of North 12a. 64 , Guide to the Invertehrata. Bryozoa. America ; its importance to English students is largely due to the GALLEKY fact that it includes specimens belonging to genera found also in England, but which are here in such unsatisfactory preservation cases that their structure cannot be adequately determined. sea & 86b, The Carboniferous fauna of ]!^orth America contains some 12a. remarkable forms, notably the screw-like Archimedes Wortheni, from Warsaw, Illinois, and Evactinopora quinqueradiata, from Burlington, Illinois. A collection from the Bathonian deposits of Northern France on the middle slope contains several interesting forms, notably two species, Memlranipora jurassica and Onychocella JlabelU- formis, which are the first known representatives of the true Cheilostomata. Among the Tertiary Bryozoa, the large specimens from the Miocene deposits of the Mediterranean are most worthy of notice. (Division A.— ARTHEOPODA.) GALLERY This division comprises the Insecta, the Myriopoda, the Arachnida, and the Crustacea. In these animals the body is 12 Table- composed of a series of segments united together in a linear order case 85. and the number of which is usually definite. Each segment may have a single pair of jointed appendages articulated to it, and both are encased in a chitinous or calcareous covering more or less thick. The muscles, nerves, and internal organs are all enclosed within the hard external covering, which thus protects them from injury. The breathing organs, when present, may be in the form of gills or branchiae, or pulmonary sacs or tracheee. III.— TRACHEATA. Fossil I — Insecta (or Hexapoda). The Insects form the most specialized _ , ' group of the Arthropoda. The head, thorax, and abdomen are Wail -Case 12, Table- distinct ; there are three pairs of legs borne on the thorax ; the case 86. abdomen has no limbs; the head bears a single pair of antennae; most insects have two pairs of wings on the thorax, and they breathe by means of trachese. The earliest known evidence of insect-life is the wing of a supposed cockroach discovered by Dr. Chas. Brongniart in the Middle Silurian of Jurques, Calvados, France, and named Falceo- hlattina Bouvillei. The Coal-measures of Commentry, AUier, Fossil Insects. 65 France, have yielded by far the largest and most wonderful GALLERY collection of fossil insects known, embracing Neuroptera, Pseudo- j^^^g^'^g orthoptera, Orthoptera, and Homoptera. One dragon-fly from ^all-case Commentry measures 28 inches in the spread of its wings. In 12, Table- the collection are displayed examples of cockroaches from the ^^^^ ^^' ■..:^^^c^,i^adB*^ Fjg. 108. — Wing oi Ooi (/(uin.t j)KJN(/niar/i, Mantell. Coal-measures: Coalbrookdale, Shropshire. Coal measures of Dudley ; of the wings of Brodia priscoUncta, from Tipton, Staffordshire (Fig. 109), showing colour- spots ; of Lithomantis carhonarius (Woodw.), from the Coal-measures of Scotland; of Corydalis Brongniarti, from Coalbrookdale (Fig. 108); and many other examples. Fig. 109. — Wing of Brodia priscotinetd, Scudder. Coal-measures: Tipton, Staffordshire. Showing evidence of colour-bands on the wing. In the Lithographic Stone (Lower Kimeridgian) of Solen- hofen and of Eichstatt, Bavaria, numerous very beautiful and well-preserved insect-remains have been met with ; many of these may be seen in Wall-case 12. The most interesting are the remains of numerous Libellulae (Dragon-flies) ; of Pygolampis gigantea^ Miinster ; of Cicada^ Gryllacris, etc. Insects occur in the Stonesfield Slate and in the Purbeck Beds : see Table-case 85. Table- In the Tertiary strata remains of insects are very numerous, and *'*^® ^^• comprise almost every existing type. Fossil-remains of many 66 GALLERY VIII. East Side. Wall-case 12, Table- case 85. Guide to the Invertehrata. Some Fossil Cockroaches from the Coal-meastjees. Fig. 110. — Etohlattina Mazona, Scudder. Carboniferous: Illinois, U.S. '^ir^-^^ Fig. Ill, — Names of veins in tbe wing of a Palaeozoic Cockroach. (After Scudder.) Fig. 112. — Progonoblattina JS'elvetwa, Hear, sp. Carboniferous : Switzerland. (Restored.) Fig. 1 13.— Wing of Cockroach, Mylacris anthracophilum, Scudder. Carbon- iferous : Illinois, U. S. Myriopoda, 67 species may be seen from the Eocene of the Isle of Wight ; from GALLERY the Miocene of CEningen, Switzerland ; from the Brown Coal of j.^^^ g^^^ Bonn ; from Aix, in Provence ; from Haring, in the Tyrol ; from the Wall-eaw Baltic Amber deposits; and from Florissant, in North America. 12, Taila- case 85. Fig. 114. — Acantherpestes major, M. and W. Coal-measures: Illinois, U.S.A. Showing the legs and the branched spines and branchial openings. (Nat. size.) Fig. 115. — Uuphoberia ferox, Salter. Coal-measures: Coalbrookdale, Shropshire. (Nat. size.) 2. — In the Myeiopoda the head is distinct, but the remainder of the body is composed of a series of similar segments, and there is no 68 Guide to the Invertehrata. GALLERY distinction between the thorax and the abdomen ; there is one pair VUI . . . East Side. ^^ antennse, and the number of legs is more than eight pairs. Wall-case This division is represented by the Centipedes and Millipedes ; and 12, Table- the earliest examples known fossil occur in the Coal-measures (Figs. 114, 115). Some North American species were of large size, and the body was armed with a row of branched spines. Specimens of them, named Euphoheria armata, from Tipton, Staffordshire, and others of E. Brownii, from Glasgow, are exhibited in Table-case 84. 3. — In the Aeachnida are included Spiders, Scorpions, Mites, etc. The body is composed of a variable number of segments, some of which carry jointed appendages. The Arachnida breathe by pulmonary vesicles or sacs, or by ramifying tubes fitted for Fig. 116. — JEophrynus Prestvicii, H. Woodw., sp. (a) the upper and {h) the under side of the same specimen ; preserved in a nodule of clay ironstone, from the Coal-measures, Shropshire. (Nat. size.) breathing air directly. There are only four pairs of ambulatory legs, and none attached to the abdomen ; they have no antennae. Of the spiders (Araneidge), three are known from the Coal- measures, namely, the Protolycosa anthracophila, Roraer, from Silesia, the Arthrolycosa antiqua, Harger, from Illinois, and an Aranea from the Coal of Bohemia. Spiders occur in the Tertiary rocks in great abundance, and examples may be seen from the Isle of Wight, from Baltic Amber, from the Miocene of OEningen, from Bonn, etc. One of the most interesting forms from the Coal-measures, belonging to the family Eophrynoidea, is the Eophrynus Prestvicii, Buckl., sp., which is preserved in a clay- ironstone nodule from near Dudley, and exhibits both upper and under surfaces of the same specimen. (See Tig. 116.) Arachnida — Scorpions. 69 ScoEPiONS.— In the Scorpionidse, the head-shield is of moderate GfALLERY VIII. size, having a pair of larger ocelli, or simple eyes, near the centre jj^^^ gj^^^ Wall- ease 12, Table- case 85. Fig. 117. — Scorpio afer,'L\m\.. Recent: Fig. 118. — Palceophoneus, sp. Upper Africa, m, maxillary palpi ; c, cheli- Silurian : Lesmahagow, Lanark*- cerae ; t, the telson. (Reduced in size.) shire. ( x f .) Fig. 119. — jEoscorpi?^s carbonarius, Meek and Worfhen. Carboniferous: Illinois. (Nat. size.) (After Nicholson's Palaeontology). 70 Guide to the Invertehrata. GALLERY of the shield, and a row of smaller ones near the front margin. Eas?^Side "^^ere are no antennae, but a pair of chelicerse on the front of the WaH-case l^ead, followed by two large clawed limbs (maxillary palpi); 12, Table- behind these are the four pairs of walking-legs. The seven ^^^^ ' thoracic segments behind the head are broader than the rest of the body, and carry upon their under-side the posterior legs, the so-called combs, and the generative organs, and four pairs of stigmata opening into lung-sacs. The abdomen consists of six narrow, elongated segments, without appendages ; the terminal one having a recurved poison-spine at its extremity (Fig. 117, t). The scorpions are a very ancient tribe of air-breathers, having been met with fossil as far back in time as the Upper Silurian in Scotland, Gothland, and North America ; they are also represented in the Coal-measures of England, Scotland, and Bohemia. (See Table-case 85 and Wall-case 12.) IV.—CRUSTACEA. This class, represented by the Crab and Lobster and a great variety of other crust-clad animals with jointed limbs, is essentially fitted to inhabit the water, breathing by means of branchiae, or gills. The entire body is usually encased in a hard structure, quite different, however, from the shell of the whelk or the oyster. This defensive envelope protects the softer parts of the body, and also covers the limbs, affording by its overlappings, infoldings, and projections, points of internal attachment for the muscles which move the legs and other organs of the animal. A cursory examination of a lobster, prawn, or shrimp, will show that, like the insects, the body-covering is made up of a number of rings or segments jointed together, to which the feelers, claws, and legs are united by means of movable sockets. To give greater pro- tection to the soft parts of the body, it often occurs that several of these body-rings are soldered together into one piece, as in the crab and lobster; but as all these animals have one pair of jointed limbs to each ring or segment of their bodies, if we find a portion like the lobster's head-shield (called the cephalothorax), which has several pairs of limbs attached to it, we know that this part of the animal is composed of several separate rings or segments united together. There are some Crustacea (e.g. Squilla, Talitrus) in which the separate rings can nearly all be seen and counted. In the higher forms, known as the Malacosteaca, there are usually thirteen Crustacea — Ostracoda. 71 segments referred to the head and thorax (cephalothorax), whilst GALLEEY the remaining six belong to the hinder part of the body called j.^g^ g^'^^ the abdomen (or pleon). Owing to the hard external covering -^all-cases possessed by nearly all the class, and to the fact that they mostly 13 & 14, lead an aquatic existence, they are very abundantly represented cases in a fossil state in many geological deposits. 80-85. (I) Entomostraca. — In the older formations in which Crustacea are met with, they all belong to the section Entomostbaca, in which the body-segments are usually indefinite in number, and the limbs are very varied in character, the most important being attached to the head, the bases of the limbs serving also as mouth-organs. 1. — OsTEAcoDA. In the Ostracoda the entire body is enclosed in a shelly carapace, composed of two valves united along the back Fig. 120. -Small bivalved forms of Crustacea : Cladocera, Ostracoda, and Copepoda. 1. Daphnia pulex, Linn, 2. Candcna hispida, Baird. 3. Cyclops quadricornis, Linn, a, an adult female ; b, c, d, larval stages. Figs. 1, 2, and 3 are all fresh-water forms. U- Cetochilus sepfentrionalis, Goodsir. Firtli of Forth. 5. Sapphirina ovatolanceolata, Dana. Atlantic. 6. Nicothoe Astaci, Aud. and Edw., parasitic, found on gills of the lobster. 7. Nauplius stage of a Copepod. by a membrane ; the valves can be closed or opened at will, and the appendages, with which the animal can either creep or swim, are protruded from the lower border. These small crustaceans first appear in the Lower Cambrian ; they are met with subsequently in rocks of almost all ages, and are equally abundant living to-day both in seas and lakes. They must be looked upon as one of those 72 Guide to the Invertelrata, Table oases 80-85 GALLEBY persistent types which possess enormous powers of multiplication, East Side ^^ ^^^* entire beds of rocks may be said to be composed of their Wall-cases naicroscopic shelly coverings. The living species are known also 12-14, to possess exceptional powers of endurance, and have special pro- vision for the preservation of their lives in periods of drought; the eggs retaining their vitality in a dormant state for years. Eepresentatives of these, as Leper ditia, Beyricliia, Bairdia, Aristozoe, Carbonia, Candona, Cypridea, Cythere, Cypris, Frimitia, and many others, may be seen in the table- and wall-cases; they occur in rocks of nearly every age. 2. — CoPEPODA. In the order Copepoda are placed numerous small crustaceans, met with in incredible numbers both in fresh and salt water. The fresh- water Cyclops (Fig. 120, 3), for example, is very abundant in ponds and rain-water tanks ; and the Cetochilus (Fig. 120, If), although so minute, colours the sea with a reddish hue for miles, and furnishes by its vast numbers abundant food for so large a mammal as the ''right whale." They have not been detected fossil in any of the rocks. In the Cladoceba the head and antennce project, but the rest of the body is entirely enclosed within a bivalved carapace ; the antennae are large and branching, and serve as swimming-organs. Daphnia pulex (Fig. 120, i), "the fresh- water flea," is a good example. It occurs in vast numbers in fresh- water ponds, but is not known in a fossil state. 3. — The Phtllopoda are Entomostracous Crustaceans having a shell composed of two valves in which the body is more or less completely enclosed, or it may form a buckler-like shield over the forepart of the animal. The gills are attached to the feet. Those living at the present day are found inhabiting both fresh water and the sea, and are of small size. Protoearis Marshii occurs in the Lower Cambrian of North America, and resembles the modern Lepidurus and Apus (Fig. 121, 3, If). The living Brauchipus (Fig. 121, 5), or Cheirocephalus, and Artemia are unprotected by any shelly covering ; but a fossil Branchipus, named Branchipodites vectensis, has been discovered in the Eocene of the Isle of Wight (Table-case 85). Species of the genus Estheria are met with in the Devonian and Carboniferous, and in all the subsequent formations even to the recent seas where it is now living. 4. — The order Phyllocaeida was founded to include the living genus Nehalia (see Fig. 121, 2), with certain extinct forms believed to be related to it, and which are considered to occupy an Crustacea — Entomostraoa. 78 intermediate position between the Phtllgpoda. and the higher GALLEBY Malacostraca (such as Mysis and Byastylis), though they certainly appear to be more nearly related to the former (the Phyllopods). i2-14 The living Nehalia is a small marine crustacean, but the giant Table pod-shrimps, such as Ceratiocaris Ludensis, from the Silurian of 8o_85^ Ludlow, attained a length of 2 feet. Other Palaeozoic examples are Jsoxys Chilhoweana (Walcott), from the Lower Cambrian ; Symenocaris vermicauda, from the Upper Cambrian ; and Ceratiocaris papilio (see Fig. 121, ^Z), from the Upper Silurian of Lanark. There are also Bithyrocaris, Aptychopsis, and many other genera ranging from the Cambrian to the Carboniferous period ; they have not been met with in later rocks. Fig. 121. — Entomostracous Crustacea. Phyllocarida. 1. Ce7'atiocaris papilio, Salter. Upper Silurian : Lesmahagow. (T^^ij- nat. size.) 2. Nebalia hipes, Fabr. (living) ; half of carapace removed to show the body and appendages. Phyllopoda. 3. Lepidurus Angasii, Baird. a, dorsal aspect (adult) ; b, ventral aspect. 4. Larva of Apus cancriformis, Schsefi'er. 5. Branchipus [Cheirocephalus) stagnalis, Milne-Edw. a, adult female ; b, c, larvae. 6. Larva of Artemia salina. Leach. 5. — Trilobita. The Trilobites form a very large but extinct order of Entomostraca, the exact position of which was for a long time a matter of doubt, as no appendages had ever been found with any of them. By the recent discoveries made in North America,* > E. Billings in 1870; C. D. Walcott in 1881; W. D. Matthew in 1893; C. E. Beecher in 1894. 74 Guide to the Invertebrata. GALLERY we now have a very complete knowledge of Triarthrus Becki, East Side. ^^"^™ ^^^ Ordovician formation of Home, New York, and a more "Wall-cases ^^ ^^^^ complete knowledge of Asaphus, Calymene, Ceraurus, 13 & 14, Trinucleus, etc. The fii st pair of antennae have a simple, many- jointed lash (or flagellum) attached to the under-side of the head on each side of the upper lip {hypostome). The second pair of antennae have two branches, and the basal joint is triangular in shape and bears a masticating edge. The third pair of limbs are also biramous and correspond with the second pair, and may be compared with the mandibles of other Crustacea, being mouth- organs at their base. Two pairs of gnathites, or maxillce, follow ; 80-82. (1) (2) Fig. 122. — Triarthrus Becki, Green. Utica Slate (Ordovician) : Eome, New York. (a) Original specimen figured by Walcott. (1) Upper and (2) under side (restored by Dr. C. E. Beecber). they resemble the second and third pairs, but are somewhat larger ; they all are used as mouth-organs, assisting in mastication. Behind them is placed a small oval metastoma, or lower lip. Fourteen pairs of biramous legs follow, each limb having a seven-jointed walking- leg (the endopodite) and a swimming-branch fringed with hairs (the exopodite) attached to its base. The anterior legs are the longest, the others very gradually becoming shorter towards th6 pygidium. The pygidium carries six pairs of appendages, each of which is also biramous, but the joints are transversely expanded so as to form broad lamellae which probably assist in respiration, Crustacea — Trilohita. 75' also as swimmerets, and in the female to support the eggs. In many GALLERY respects the Trilobites are very near in structure to the modern Apus. -^^^^ ^^^^ The great variability in the number of segments in Trilobites wallcases had long ago led to the conclusion that they were phyllopods ; 13 & 14, a knowledge of the simple biramose character of their limbs, as cases well as the gradual diminution in the size of the segments, and 80-82. their appendages, from the head to the pygidium (a feature which Fig. 123. — Olenellus Callavei, Lapw. Fia. 124. — Paradoxides Bavidis, Salter. Lower Cambrian : Shropshire. M.Cambrian: St. Davids. Fig. 125 — Agnostus princeps, Salter. Cambrian : S. Wales. Fig. l26.—Olenus. Upper Cambrian. Fig. 127. — Ogygia Buchii, Brong. Ordovician : Llandeilo. 76 Guide to the Invertebrata. GALLERY the Trilobites share with Apus), entirely confirms this conclusion. East Side P^^obably two thousand species and over one hundred genera of "Wall-cases Trilobites are known from Palaeozoic rocks. They first appear 13 & 14, in the Lower Cambrian, attaia their maximum development in cases ' ^^^ Silurian ; about four genera continue on into the Carboniferous 80-82. period, after which they entirely disappear. Fig. 128. — Calymene Blu- menbachii, Brong. Upper Silurian: Dudley. Fig. 129. — Acidaspis mira., Beyr. Upper Silurian: Dudley. Fig. 130. — Staurocepkalus Murchisoni, Barr. Upper Silurian: Dudley. Fig. 131. — Homalomtus delphinocephalus, Green, Upper Silurian : Dudley. Fig. 132. — Brontem Jlabellifer, Goldf. Devonian: Newton, Devon. Fig. 133. — Br achy me- topus Ouralicus,V orH. Carboniferous Lime- stone : Settle, York- shire. Crustacea — Merosfomata. 77 (II) Meeostomata. — Immediately following the Entomostraca are GALLERY the Merostomata, a very remarkable ffroup of Crustacea, some of . . . . . . Wall-cases which are of gigantic size. The mouth is furnished with mandibles ^3 g^ ^4 Fig. \Si.—GriJit?iides Fig. 135. — Phillipsia Eichwaldi Fig. U6.—Fhillipsia De,'" fflobiceps, Vortl. Car- var. mucronata, M'Coy. biensis, Martin. Car- boniferous Lime- Carboniferous Limestone boniferous Limestone : stone : Ireland. shale : Muirkirk. Derbyshire. "Wall-cases 13 & 14, Table- cases 80 & 82, and Gal- lery-walls between Wall-cases 12 & 13, andl3&14. Fig. 137. — Pterygotus anglicus, Ag. (under-side). Old Red Sandstone : Forfar- shire. 1, the compound sessile eyes; 2, the chelate antennae; 3, 4, 5, the mandibles, maxillae, and maxillipedes ; 6, the great swimming jaw- feet ; m, the metastoraa, or lower lip ; 7, the operculum, covering the reproductive organs (8) and the gills (9) ; the other segments (10-19) are destitute of any appendages ; 20, the telson, or terminal segment. 78 Guide to the Invertehrata. Crustacea, and maxilloe, the terminations of which become walking or GALLERY swimming legs, or organs of prehension. The Merostomata include East Side. ^^^ orders, namely, the Eurypteeida and the Xiphosuea (king- Wall-cases crabs). These are all aquatic, the former being extinct, whilst T^w ^^' ^^^ latter (the king-crabs) are still living. cases 1- — The Eueypterida have an elongated flattened form, the 80-82. body tapering towards the tail and having a peculiar scale-like ornamentation upon its hard covering. The head-shield bears a pair of compound eyes, and two minute ocelli on its upper surface, and covers only the mouth with its large lower lip {metastoma) and five pairs of jaw-feet, which are also the only Fig. 138. — Limulus polyphemus, Latr. Eecent: North America, a, dorsal aspect of shields ; b, ventral aspect, showing appendages and branchial lamellae. locomotory organs. One or more of the segments, which follow next after the head, usually bear divided lamellae, covering the gills, attached upon their under surface ; the other nine or ten segments are without any appendages ; and the body terminates in a spine-like or paddle-shaped telson (Fig. 137). The Eurypterida — represented by Pterygotus, Slimonia, Eurypterus^ Stylonurus, Semiaspis, etc. — appear first in the Silurian (Upper Llandovery), and are represented in the succeeding Devonian rocks, and on into the Lower Carboniferous epoch. The largest forms have been met with in the Old Eed Sandstone of Forfarshire, some attaining nearly six feet in length. (See Table-case 80 and Wall-cases 13, 14.) Crustacea — Xiphosura and Cirripedia. 79 2. — In the Xiphosuea (king-crabs) the head-shield forms a Crustacea, large semicircular buckler (Fig. 138(?), bearing a pair of compound GALLERY eyes and two minute ocelli upon its upper surface, and covering East Side, beneath its convexity (Fig. 138 J) the mouth with its rudimentary Wall-cases lower lip (metastoma) and six pairs of feet, all but the first of }^^ ^^' which act as masticatory organs at their bases, and are also the cases only locomotory organs. The body-segments in living king-crabs 80-82. are fused together, and carry six leaf-like plates upon their under-side, each bearing the branchiae or gills attached to their inner surface. In the larval king-crab, and in some fossil species, these posterior segments of the body were freely articulated, not soldered together into one piece. The last segment of the body forms a long, sword-like, movable telson, or tail-spine. King- crabs first appear in the Upper Silurian ; they are found in the Carboniferous period, in the Oolitic, Cretaceous, and Tertiary periods, and living on the coasts of America and China at the present day. (See Table-case 80 and Wall-case 13.) (Ill) Anchoeacephala.. — This section includes the Ehizo- Cirripedes, CEPHALA and the Cieeipedia. The Rhizocephala and Cirripedia ^^l^^^^®? and have free-swimming larvae, resembling ordinary bivalved Entomo- Lepadidae. straca ; but the former, when adult, have no mouth, lose all their limbs, and attach themselves by root-like processes to some living Table-case Crustacean, upon the juices of which they subsist; the latter attach case 12c. themselves, when adult, to rocks, shells, drift-wood, ships, etc., and develop a peculiar multi valve shell, either fixed upon a stalk (pedunculated, Lepadidce) — "Barnacles " — or attached directly to the stone or wood by the surface of their own shell (sessile, Balanidce) — "Acorn-shells." These animals possess long cirri, which they protrude from their shell, and by the constant movements which they keep up convey in a current the food-particles to their mouth within the valves of their shell. The Rhizocephala are not found fossil ; but the remains of Cirripedia occur both in Secondary and Tertiary strata, and have been admirably described by Charles Darwin. One form referred to the Cirripedia, named Turrilepas, has been met with in the Upper Silurian of Dudley, etc. (lY) Malacosteaca. — Passing from the Entomostbaca and their allies, to which nearly the whole of the older fossil forms of Crustacea belong, we arrive at the Malacosteaca, the next and higher division. &84. 80 Guide to the Invertehrata, Crustacea. In these the head and trunk (cephalothorax) is composed of thirteen GALLERY segments ; the abdomen (or pleon) of six segments and a " telson" or East Side tail-spine. The Malacostraca are divided into two orders — (1) the Table- Edkiophthalma, in which the eyes are sessile or fixed on the cases surface of the head, and the head and thorax are distinct; and (2) the PoDOPHTHALMA, in which the eyes are movable, being fixed on a peduncle or stalk (hence called "stalk-eyed Crustacea"), and the head and thorax are generally united to form a cephalothorax. (a) Edkiophthalma: 1. — Amphipoda. The animals of this division are small in size ; the body is compressed laterally. They are mostly found in the sea, or on its shores, where they abound. The common " sand-hopper" is a good example. One form, named Necrogammarus Salweyi, occurs in the Lower Ludlow, Shropshire ; Gampsonyx fitnhriatu8 in the Coal-measures of Rhenish Prussia; and Prosoponisous proUematicua in the Permian of Durham. Yarious Tertiary Amphipods have been described. Fig. 139. Fig. 140. Falctga Carteri, H. Woodward. ^ga moxophthalma, Johnston. Grey Chalk: Dover. Recent: Moray Firth. 2. — IsopoDA. The Isopods have seven pairs of walking - legs on the seven thoracic segments, which never bear gills ; these are always attached to the appendages of the pleon or abdomen. Frearcturus gig as occurs in the Old E,ed (Devonian) of Hereford ; Bostrichopus antiquus in the Devonian of I^assau. Tru'B Isopods are known from the Jurassic rocks ( Cyclosphceroma trilohatum), North- ampton, and from Solenhofen ; Archcsoniscus Brodiei, from the Purbeck of Wilts and Dorset. A parasitic form {Bopyrus) occurs fossil under the carapace of Palc&ocorystes, from the Greensand Crustacea — Malacostraca. 81 of Cambridge. Several forms occur fossil in the Chalk and Crustacea. Tertiaries ; as Falcega Carteri, Grey Chalk, Dover (Fig. 139), and CrALLERY Eosph