Below in the vertebræ of the posterior half of the body the _hæmapophyses_ (69) unite to form the _hæmal spine_ (70), and through the _hæmal canal_ thus formed passes a great artery. The vertebræ having hæmal as well as neural spines are known as _caudal vertebræ_, and occupy the posterior part of the body, usually that behind the attachment of the _anal fin_ (78). The anterior vertebræ known as _abdominal vertebræ_, bounding the body-cavity, possess neural spines similar to those of the caudal vertebræ. In place, however, of the hæmapophyses are projections known as _parapophyses_ (72), which do not meet below, but extend outward, forming the upper part of the wall of the abdominal cavity. [Illustration: FIG. 32.--Pharyngeals of Italian Parrot-fish, _Sparisoma cretense_ (L.). _a_, upper; _b_, lower.] To the parapophyses, or near them, the ribs (73) are rather loosely attached and each rib may have one or more accessory branches (74) called _epipleurals_. [Illustration: FIG. 33.--_Roccus lineatus._ Vertebral column and appendages, with a typical vertebra. (After Starks.) 64. Abdominal vertebræ. 65. Caudal vertebræ. 66. Centrum. 67. Neurapophysis. 68. Neural spine. 69. Hæmapophysis. 70. Hæmal spine. 71. Zygapophysis. 72. Parapophysis. 73. Ribs. 74. Epipleurals. 75. Interneural. 76. Dorsal fin. 77. Interhæmal. 78. Anal fin. 79. Hypural. 80. Caudal fin.] In the striped bass the dorsal vertebræ are essentially similar in form, but in some fishes, as the carp and the catfish, 4 or 5 anterior vertebræ are greatly modified, coossified, and so arranged as to connect the air-bladder with the organ of hearing. Fishes with vertebræ thus altered are called _plectospondylous_. In the garpike the vertebræ are convex anteriorly, concave behind, being joined by ball-and-socket joints (opisthocoelian). In most other fishes they are double concave (amplicoelian). In sharks the vertebræ are imperfectly ossified, a number of terms, asterospondylous, cyclospondylous, tectospondylous, being applied to the different stages of ossification, these terms referring to the different modes of arrangement of the calcareous material within the vertebra. =The Interneurals and Interhæmals.=--The vertical fins are connected with the skeletons by bones placed loosely in the flesh and not joined by ligament or suture. Below the dorsal fin (76) lies a series of these bones, dagger-shaped, with the point downward. These are called _interneurals_ (75) and to these the spines and soft rays of the fin are articulated.