The ventral fins are articulated to a pair of flat triangular bones, the pubic bones (80).
The bones of the skull of the fish have received so many different interpretations that no two accounts agree in their nomenclature, so that their study is a matter of considerable difficulty to the beginner. The following synonymic table will tend to overcome difficulties arising from this cause; it contains the terms used by Cuvier, those introduced by Owen, and finally the nomenclature of Stannius, Huxley, and Parker. Those adopted in the present work are printed in italics. The numbers refer to the figures in the accompanying woodcuts (Figs. [23–27]).
| Cuvier. | Owen. | Stannius. | Huxley, Parker, etc. | ||||
| 1. | Frontal principal | Frontal | Os frontale | ||||
| 2. | Frontal antérieur | Prefrontal | Os frontale anterius | Lateral ethmoid (Parker) | |||
| 3. | Ethmoid | Nasal | Os ethmoideum | ||||
| 4. | Frontal postérieur | Postfrontal | Os frontale posterius | Sphenotic (Parker) | |||
| 5. | Basilaire | Basioccipital | Os basilare | ||||
| 6. | Sphénoide | Basisphenoid | Os sphenoideum basilare | Sometimes referred to as “Basal” | |||
| 7. | Pariétal | Parietal | Os parietale | ||||
| 8. | Interpariétal or occipital supérieure | Supraoccipital | Os occipitale superius | ||||
| 9. | Occipital externe | Paroccipital | Os occipitale externum | Epioticum (Huxley) | |||
| 10. | Occipital lateral | Exoccipital | Os occipitale laterale | ||||
| 11. | Grande aile du sphénoide | Alisphenoid | Ala temporalis | Prooticum (Huxley) | |||
| 12. | Mastoidien | Mastoid | Os mastoideum + os extrascapulare |  | Opisthoticum[5] +Squamosal (Huxley) | ||
| 13. | Rocher | Petrosal and Otosteal | Oberflächliche Knochen-lamelle | ||||
| 14. | Aile orbitaire | Orbitosphenoid | Ala orbitalis | Alisphenoid (Huxley) | |||
| 15. | Sphenoide antérieur | Ethmoid and Ethmoturbinal | Os sphenoideum anterius | Basisphenoid (Huxley) | |||
| 16. | Vomer | Vomer | Vomer | ||||
| 17. | Intermaxillaire | Inter- or Pre-maxillary | Os intermaxillare | ||||
| 18. | Maxillaire supérieur | Maxillary | Os maxillare | ||||
| 19. | Sousorbitaires | Infraorbital ring | Ossa infraorbitalia | ||||
| 20. | Nasal | Turbinal | Os terminale | ||||
| 22. | Palatine | Palatin | Os palatinum | ||||
| 23. | Temporal | Epitympanic | Os temporale | Hyomandibular (Huxley) | |||
| 24. | Transverse | Pterygoid | Os transversum s. pterygoideum externum | ||||
| 25. | Ptérygoidien interne | Entopterygoid | Os pterygoideum | Mesopterygoid (Parker) | |||
| 26. | Jugal | Hypotympanic | Os quadratojugale | Quadrate (Huxley) | |||
| 27. | Tympanal | Pretympanic | Os tympanicum | Metapterygoid (Huxley) | |||
| 28. | Operculaire | Operculum | Operculum | ||||
| 29. | Styloide | Stylohyal | Os styloideum | ||||
| 30. | Préopercule | Præoperculum | Præoperculum | ||||
| 31. | Symplectique | Mesotympanic | Os symplecticum | ||||
| 32. | Sousopercule | Suboperculum | Suboperculum | ||||
| 33. | Interopercule | Interoperculum | Interoperculum | ||||
| 34. | Dentaire | Dentary | Os dentale | ||||
| 35. | Articulaire | Articulary | Os articulare | ||||
| 36. | Angulaire | Angular | Os angulare | ||||
| 37. |  | Grandes pièces latérales | Epihyal | | Segmente der Zungenbein-Schenkel | ||
| 38. | Ceratohyal | ||||||
| 39. | | Petites pièces laterales | Basihyal | ||||
| 40. | |||||||
| 41. | Os lingual | Glossohyal | Os linguale s. entoglossum | ||||
| 42. | Queue de l’os hyoide | Urohyal | Basibranchiostegal (Parker) | ||||
| 43. | Rayon branchiostège | Branchiostegal | Radii branchiostegi | ||||
| 46. | Surscapulaire | Suprascapula | Omolita | Post-temporal (Parker) | |||
| 47. | Scapulaire | Scapula | Scapula | Supraclavicula (Parker) | |||
| 48. | Humeral | Coracoid | Clavicula | Clavicula (Parker) | |||
| 49. | | Coracoid | Epicoracoid | Postclavicula (Parker) | |||
| 50. | |||||||
| 51. | Cubital | Radius | | Ossa carpi | Coracoid (Parker) | ||
| 52. | Radial | Ulna | Scapula (Parker) | ||||
| 53. | Os du carpe | Carpals | Ossa metacarpi | | Basalia (Huxley), | ||
| Brachials (Parker) | |||||||
| 53 bis. | | Chaine intermédiaire | Basibranchials | Copula | |||
| 55. | |||||||
| 54. | |||||||
| 56. | Pharyngiens inférieurs | Lower Pharyngeals | Ossa pharyngea inferiora | ||||
| 57. | Pièce interne de partie inférieure de l’arceau branchiale | Hypobranchial | | Segmente der Kiemenbogen-Schenkel | |||
| 58. | Pièce externe „ | Ceratobranchial | |||||
| 59. | Stylet de prémière arceau branchiale | Upper epibranchial of first branchial arch | |||||
| 61. | Partie supérieure de l’arceau branchiale | Epibranchials | |||||
| 62. | Os pharyngian supérieur | Pharyngobranchial | Os pharyngeum superius | Upper pharyngeals | |||
| 63. | Gill-rakers | ||||||
| 65. | Rayons de la pectorale | Pectoral rays | Brustflossen-Strablen | ||||
| 67, 68. | Vertèbres abdominales | Abdominal vertebræ | Bauchwirbel | ||||
| 69. | Vertèbres caudales | Caudal vertebræ | Schwanzwirbel | ||||
| 70. | Plaque triangulaire et verticale | [Aggregated interhæmals] | Verticale Platte | Hypural (Huxley) | |||
| 71. | Caudal rays | Schwanzflossen Strahlen | |||||
| 72. | Côte | Rib | Rippen | ||||
| 73. | Appendices or stylets | Epipleural spines | Muskel-Gräthen | ||||
| 74. | Interépineux | Interneural spines | Ossa interspinalia s. obere Flossentræger | ||||
| 75. | Épines et rayons dorsales | Dorsal rays and spines | Rückenflossen-Strablen u. Stacheln | ||||
| 76. | First interneural | ||||||
| 78. | Rudimentary caudal rays | ||||||
| 79. | Apophyses épineuses inférieures | Interhæmal spines | Untere Flossentræger | ||||
| 80. | Pubic | Becken | |||||
| 81. | Ventral spine | Bauchflossen-Stachel |
CHAPTER IV.
MODIFICATIONS OF THE SKELETON.
The lowermost sub-class of fishes, which comprises one form only, the Lancelet (Branchiostoma [s. Amphioxus] lanceolatum), possesses the skeleton of the most primitive type.
Fig. 28.—Branchiostoma lanceolatum. a, Mouth; b, Vent; c, abdominal porus.
Fig. 29.—Anterior end of body of Branchiostoma (magn.) d, Chorda dorsalis; e, Spinal chord; f, Cartilaginous rods; g, Eye; h, Branchial rods; i, Labial cartilage; k, Oral cirrhi.
The vertebral column is represented by a simple chorda dorsalis or notochord only, which extends from one extremity of the fish to the other, and, so far from being expanded into a cranial cavity, it is pointed at its anterior end as well as at its posterior. It is enveloped in a simple membrane like the spinal chord and the abdominal organs, and there is no trace of vertebral segments or ribs; however, a series of short cartilaginous rods above the spine evidently represent apophyses. A maxillary or hyoid apparatus, or elements representing limbs, are entirely absent.