In the Cyclostomata (_Petromyzon_) these bodies are represented by lobules of cells along the posterior cardinal veins, and also by masses of peculiar cells ("chromaffin cells") along the sides of the aorta and segmental arteries.[406] In Elasmobranchs there are two distinct structures, the paired supra-renals and the inter-renals (Fig. 203, A). The former are a series of pairs of segmentally arranged bodies, situated on the successive pairs of segmental arteries given off from the dorsal aorta. The two bodies which form the first pair are much larger than any of the others, and were formerly spoken of as "axillary hearts." The inter-renal is usually a thin elongated "ochre-yellow" body, from which one or two lobes may be detached in front, and extends for a variable distance in {347}the median line between the two kidneys, or is unsymmetrically placed on the ventral surface of either kidney.[407] Sometimes (e.g. in _Raia_) the inter-renals are paired, in which case they are applied to the inner and hinder margins of the kidneys. In the Sturgeon (_Acipenser sturio_) the "supra-renals" appear as numerous "ochre-yellow" bodies, variable in size and distribution (Fig. 203, B). Some of them are visible on the surface of the kidneys, while others are scattered about in their substance, but on the whole are more anteriorly placed than in Teleosts. In the latter group the "supra-renals" are usually two in number (Fig. 203, C), but may be as many as five or reduced to one. They are disposed either on the ventral or the dorsal surface of the kidneys, generally near their hinder extremities, or more or less deeply embedded in their substance. Besides these bodies there are also chromaffin cells in the walls of the anterior cardinal veins.[408]