66 PHYSIOLOGICAL SERIES. 



B. 81. Portion of the vertebral column of a Fox Shark (Alopecias 

 vulpes) from the caudal region, showing especially the 



dorsalia and interdorsalia ; also ventralia and interventralia. 



\ 



B. 82. Portion of the vertebral column (part in section) of a 

 Porbeagle Shark (JLamna cornubica] showing a flattened 

 continuous band of yellow elastic tissue closely adherent to 

 its cartilaginous spinous processes. The biconcave (amphi- 

 coelous) vertebral bodies are well developed. Their cartilage 

 is calcified on their articular surfaces, and around the 

 sheath of the notochord, from which point four sets of 

 calcareous plates extend to the circumference, their intervals 

 being occupied by cartilage. The cartilaginous neural 

 arches (dorsalia and interdorsalia) show the openings for the 

 dorsal and ventral roots of the spinal nerves, into the former 

 green and into the latter red glass rods have been introduced. 

 On either side of the ventral surface of the column are 

 cartilaginous plates, the ventralia and interventralia. 

 Hasse, Nat. Syst. Elasmobranchier, 1882, p. 214. 



B. 83. Transverse section of the vertebral column of a young 

 Basking Shark (Selaclie maxima) that measured twelve feet 

 in length. The notochord is continuous, enlarging at 

 intervals to form the soft intervertebral discs. Concentric 

 rings of calcification traverse the cartilaginous body. 

 These rings are interrupted by the cartilaginous con- 

 tinuations of the neural arches (dorsalia) and transverse 

 processes (ventralia). The concentric plates are in later 

 life followed by radiating ones. 0. C. 237 B a. 

 Hasse, Nat. Syst. Elasmobranchier, 1882, p. 236. 



B. 84. Transverse section of half a vertebra of an older example 

 of a Basking Shark (S. maxima) showing the radiating 

 plates of calcified cartilage that invest the concentric ones. 

 There are also fine radiating lines of calcification between 

 the concentric plates. 



B. 85. Terminal caudal vertebrie of a Piked Dog-fish (Acanthias 

 vulgaris) showing besides the vertebrae, the horny fila- 

 ments that support the extreme edge of the fin-membrane. 

 0. 0. 279 D. Presented l>y W. Clift, Es<}. 



Hasse, Nat. Syst. Elasmobranchier, 1882, p. 93. 



