400 FCETAL DY ST OKI A. 



b, H. tetrasulns dipygus (with a double croup) ; H. triscekis (with three 

 posterior Hmbs). 



OEDEE V. — Monstrosities w^th a Single Head and Tkunk, and 

 MOKE THAN FouB LiMBS — Melocliclymi: — 



12. — Opisthomelophokus. — An animal regularly formed, but which 

 bears on its back or croup a supernumerary limb or limbs ; 3 species : 

 O. trichirus (with an anterior limb on the back), 0. tetrachirus (with 

 two anterior limbs on the back), 0. tetrascelus (with two posterior limbs 

 on the croup). 



13. Emprosthomelophorus. — With a supernumerary limb or limbs 

 on the neck, thorax, or beneath the pelvis ; 5 species : E. octipes (with 

 four supernumerary limbs beneath the thorax), E. trichims (with an 

 anterior limb on the thorax), E. tetrachirus (with two anterior limbs on 

 the neck), E. triscchis (with a posterior limb beneath the pelvis), E. 

 tetrascelus (with two posterior limbs beneath the pelvis). 



14. Pleuromelophorus. — With a supernumerary limb or limbs 

 situated on the side ; 4 species : P. octipes (with four limbs on the side), 

 P. tetracliirus (with two anterior limbs on the side), P. trichirus (with 

 an anterior supernumerary limb), P. triscclus (with a posterior super- 

 numerary limb). 



OEDEE VI. — Monstrosities with the Head, Trunk, and Limbs 

 MORE OR less COMPLETELY DouBLE — Somatodiclymi :— 



15. Octopus. — With eight limbs ; 4 species : 0. janus (two faces 

 placed opposite each other, and eight limbs), 0. quadriauritus (eight 

 limbs and four ears), containing two varieties : a, 0. quadriauritus 

 monoprosopus (with a perfect face) ; b, 0. quadriauritus aprosopus (face 

 absent) ; 0. biauritus (eight limbs and two ears), 0. synapheocephahis 

 (eight limbs, and the heads joined externally only by the skin). 



16. Tetrachirus. — With four anterior limbs ; 2 species : T. sympho- 

 cephalus (four anterior limbs, two lateral and two incomplete, on the 

 back, and heads joined), T. choristocephalus (four anterior limbs, and 

 heads separate). 



17. Tetrasculus. — With four posterior limbs ; 2 species : T. sympho- 

 cephalus (four posterior limbs, and heads united), T. bifacialis (four 

 posterior limbs, and the two faces separate). 



18. Gastkodidymus. — Twins united at the abdomen ; 3 species : 

 G. quadrupes (twins united at the abdomen, and furnished with four 

 limbs), G. tetrachirus (with four anterior limbs), G. octipes (with eight 

 hmbs). 



19. Gastro-Thoracodidymus. — Twins united at the thorax and abdo- 

 men ; 1 species : G. thoracodidymus octipes (with eight limbs). 



20. Epigastkodidymus.- — Twins united at the thorax and epigastrium ; 

 1 species : G. octipes (wdth eight limbs). 



21. Thoracodidymus. — Twins united at the thorax; 1 species: 

 T. octipes (with eight limbs). 



22. Schelodidymus. — Twins united at the posterior extremities ; 

 1 species : S. hcptamelus (with seven limbs, the posterior pair being 

 united into one, the next pair at the side, and the other four in front). 



23. Ischiodidymus. — Twins uaited at the pelvis; 1 species: /. ex- 

 avielus (with six limbs, four anterior and two posterior). 



24. Omphalo-Chronodidymus. — Twins united at the umbilicus and 

 the head ; 1 species : 0. disomatus (the bodies separate). 



