pCAl 



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roNTKNTS OF VOL. IV. 



PASS 



Chapter XXIX. AMPHINEURA. By E. Korschelt .... 1 



I. The development of Chiton 2 



1. The cleavage and the formation of the germ-layers . . 2 



2. The development of the larval form ..... 4 



3. The further development of the larva and metamorphosis . 6 

 II. The development of Dondersia ....... 15 



Literature ........... 20 



Chapter XXX. LAMELLIBRANCHIA. By E. Korschelt . . 22 



1. Oviposition and care of the brood ...... 22 



2. Cleavage and formation of the germ-layers .... 24 



3. Development and structure of the Trochophore larva . . 30 



A. The Trochophore stage as a free-swimming larva . . 30 



B. The Trochophore stage of fresh-water Lamellibranchia . 39 



4. The transformation into the adult ...... 41 



Divergencies in the metamorphosis accompanying the 



Monomyarian condition ....... 46 



5. The development of the Unionidae ...... 49 



A. Development of the early stage ..... 50 



B. The development of the embryo into the parasitic larva 52 



C. The transition to the adult ...... 57 



6. The formation of the organs 60 



A. The shell 60 



B. The nervous system . . . ' . . . . .62 



C. The sensory organs ........ 63 



The eyes of Pecten ....... 64 



The otocysts 66 



Spengel's olfactory organs, abdominal sensory organs . 66 



D. The alimentary canal . 66 



E. The gills 68 



F. The body-cavity, the blood-vascular system and the 



kidney 73 



The formation of the heart . . . . . .76 



G. Musculature and connective tissue . .... 81 

 H. The genital organs 82 



Literature 83 



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