400 



FCETAL DYSTOKIA. 



— it is united to the corresponding part of the second jaw, with which 

 it forms an acute angle). 



ORDER III. DOUBLED-HEADED MONSTROSITIES, WITH THE TrUNK 



WHOLLY OR PARTIALLY DOUBLE : 



8. DiCEPHALUS. — Two separate heads ; 7 species : D. biatlaniiciis 

 (double head and two atlases), D. subbicollis (double head with apparently 

 two necks), D. bicollis (double head and two necks), with two varieties : 

 D, bicollis omocephalus (both heads alike), Z>, bicollis heterocephalus (one 

 head perfect, the other imperfect) D. subbidorsnalis (double head, with 

 apparently a double back), D. bidorsualis (double head with double back), 



D. bilumbis (double head and double loins), D. bispinalis (double head 

 and vertebral column) has two varieties : a, D. bispinalis quadnipes (with 

 four limbs) ; b^ D. bispinalis achirus (without anterior limbs). 



9. DiCRANUS. — Double cranium ; i species : D. bispinalis (cranium and 

 vertebral column double). 



ORDER IV. — Monstrosities with a Single Head, but the Trunk 

 OR Limbs more or less Completely Double — Conno-melo- 

 didymi: — 



10. Dipygus. — Double croups ; 3 species : D. bidorsualis (double 

 croup and back), D. subbidorsualis (double croup, with half the back doub- 

 led), Z>. biliitnbis (croup and loins doubled), containing two varieties:. 

 a, D. bilumbus teleocephalus (with head regular) ; b^ D. bilumbis cacoceph- 

 alus (with head irregular). 



11. Heterodidymus. — Unequally-developed twins, the body of one 

 being large and regularly or irregularly formed, the other being small and 

 slenderly attached to some part of its fellow ; 3 species : H. octipes (with 

 eight feet), containing two varieties : a, H. octipes emprosthochirophoriis 

 (the anterior limbs of the parasitic twin situated in front) ; b^ H. octipes 



pleiirochirophorus (the anterior limbs of the parasitic twin situated at the 

 side) ; H. tetrasulus (with four posterior extremities), also containing two 

 varieties : a, H. tetrasulus monopygus (with one croup) ; b, H. tetrasulus 

 dipygus (with a double croup) ; H. triscelus (with three posterior limbs). 



ORDER V. — Monstrosities with a Single Head and Trunk, and 

 more than Four Limbs — Melodidymi : — 



12. — Opisthomelophorus. — 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), (9, tetrachirus (with two 

 anterior limbs on the back), O. 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. trichirus (with an anterior 

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



E. triscelus (with a posterior limb beneath the pelvis), E. tetrascelus (with 

 two posterior limbs beneath the pelvis). 



14. Pleuromelphorus. — With a supernumerary limb or limbs situated 

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

 chirus (v/ith two anterior limbs on the side), P. trichirus (with an anterior 

 supernumerary limb), P. triscelus (with a posterior supernumerary limb). 



