( 367 ) 



TABLE XXXIX. 



SyptPTTiatic Snrvey of the Sequence, according to Age, of the ITxnrna.n 



Oigan-sjstems. 



(Phylogenetic Classification of Vertebrate Organp.) 

 (On the right are given the AQcestral Stages, in which the respective 

 organs probably first appeared.) 



1. First Stage in the Evolution of Organs. 

 I. Skin and Intestinal Systems. 



The two Systems appear first, and simultaneously, in the Gastread ancestors. 

 ^Al. Simple exoderm Gastra'ads 



I. A. 



Skin-system 

 (^Systtma dermale) 



I. B. Intestinal system 



i^iiysteiua y ait i alt) 



A 2. Outer skin (Skin-sensory laver^ and ) ,.r 

 ) leather skin (Skin-fii runs l,,yei ) ) " """^ 



' ^ 3. Outer skin, witli hairs, glauds, eic. Rlanimah 



B 1. Simple entoderm Gastiaiads 



B2. Intestinal epithelium (Intestinal-glan-^ 



diilar layer) and intes inal muscular > Worms 

 skin (Intcstinal-tibrous layer) ) 



BZ. Gill-intestine and stomach-intestine Chorda-;iiiimal8 



2. Second Stage in the Evolution op Organs. 



II. Nerve and Muscle Systems. 



The two Systems appear first, and simultaneously, in the Primitive Worm ancestors. 



IT r Norvo svRtem ( C 1. Upper throat gmglia I'rimitive W..n> s 



u. o. ^)" Y'^^^f,™. ,,^_,^, C 2. simple medullary tube Chorda-anini..ls 



(.Systtma nerveum) | ^ 3 ^J^ ^^^ spinal ma. row Mur.orhina 



II. D. Muscle-system ( ^ l' ^^^"■™"'"/' "^flf' , ^ P.imit,ive Wo. ms 



(SyUtma muscalare) l^^l ^'^^ f^^<^\^f. "f the t rank Acrania 



vo^oicHu* «•. oi,t*^«.i cy ( i> 3. Trunk and limb muscles Fishes 



8. Third Stage in the Evolution of Organs. 



III. Kidney and Vascular Systems. 



The two Systems first appear, one after the other, in the Soft-worm ancestors {Scnlecida). 



Scolecida 

 Acrania? 

 JMonorhina 

 Protamiria 



Scolecida 

 AVorms 



Chorda-an'mal.<* 

 Wouorhina 



ITT. E. Kidney-system 

 (JSys ema renale) 



III. F. Vascular system 



{Systana vasculare') 



!E\. Primitive kidnej' canals 

 E2. Segmental canals 

 EZ. Primitive kidne3's 

 E'i. Permanent kidneys 

 (Fl. Simple coelom 

 ) F2. Dorsal and ventral vessels 



\F 



3. Heart (part of the ventral vessel) 



4. Heart, with auricle and ventricle 



4. Fourth Stage in the Evolution op Organs. 

 IV. Skeleton and Sexual Systems, 

 The two Systems first appear, one after the other, in the Chordonia-ancestors. 



rV.C Skeleton-system 



{Sydttina skeLtare) 



I V. IT. Sexual system 



{Systtma stxualt) 



(G I. Simple notochord 



) G2. (.Jartilaginous primitive skull 



J CS. Gill-arches, ribs, limbs 



\G A.. Limbs, with five digits 



fill. Simple hermaphrodite glands 

 ) i72. Distinct testes and ovaries 

 "i 7/3. Seed-duct and oviduct 

 \UA.. Phallus (penis, clitoriij) 



Choida-an'nials 

 Monorhina 

 SeLichii 

 Amphibia 



Chorda-animals 

 Acrania 

 Sc-lachii 

 Protamnia 



57 



