SOME ORGANS AND VESTIGES OF ORGANS, WHICH 
SHOW [STRUCTURAL COMMUNITY WITH] VERY 
PRIMITIVE VERTEBRATE TYPES 
CONDITIONS DEFINITIVE IN FISHES (ELASMOBRANCHS) ARE 
INDICATED BY 
(1) The free dental papille projecting above the surface of 
the mucous membrane before the sinking of the dental ridge. 
(The appearance ontogenetically of the dental ridges, long 
before the first osseous rudiments, points back to the 
extremely early phylogenetic appearance of teeth, in 
Vertebrates, before any of the other hard structures of 
the body.) . 
(2) The pineal gland and pineal organ (a parietal foramen 
in the roof of the skull is found in Fishes as early as the 
Devonian period, and the organ occurs in the Marsipobranchi1). 
(3) The pituitary body (hypophysis cerebri). 
(4) The branchial pouches. 
(5) The vessels of the visceral arch system. 
(6) The vasa hyaloidea of the vitreous body Ce LED 
canal). 
(7) The cardinal veins. 
(8) Certain structures, appearing in the development of fg 
heart, vestiges of which are found in the fully developed organ. _ 
(9) The arteria caudalis (A. sacralis media). 
(10) The pro- and meso-nephric excretcry apparatus. — 
(11) The possible vestiges of a third set of teeth (pointing 
back to a probable successive renewal of teeth, such as 
characterises Fishes, Amphibians, and Reptiles). 
