MONSTROSITIES. 401 



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

 MORE OR LESS COMPLETELY DouBLE — Somatodidymi : 



15. Octopus. — With eight limbs; 4 species: O. Janus (two faces 

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

 and four ears), containing two varieties : a^ O. quadriauritus monoprosopus 

 (with a perfect face) ; b, O. quadriauritus aprosopus (face absent) ; O. 

 biauritus (eight limbs and two ears), O. syfiapheocephalus (eight limbs, and 

 the heads joined externally only by the skin). 



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

 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.symphyo- 

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

 terior limbs, and the two faces separate). 



18. Gastrodidymus. — 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 limbs). 



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

 domen ; I species : G. thoracodidymus octipes (with eight limbs). 



20. Epigastrodidymus. — Twins united at the thorax and epigastrium : 

 I species : G. octipes (with eight limbs). 



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

 octipes (with eight limbs). 



22. ScHELODiDYMUS. — Twius United at the posterior extremities ; i 

 species : S. heptamelus (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 United at the pelvis ; i species : /. examelus 

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



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

 the head ; i species : O. disomatus (the bodies separate). 



25. Pygodidymus. — Twins united at the croup ; i species : P. aversus 

 (bodies united at the ischii and sometimes at the buttock, and in opposite 

 directions). 



26. Cryptodidymus. — Inclusion of one twin within the other ; 2 species : 

 C. abdominalis {twin included in the ^hdomtn), C. subcutaneus (\x\covs\- 

 plete foetus included beneath the skin of the complete one;. 



Such is the classification adopted by Gurlt, and it will be seen that it 

 is very complete, while the nomenclature scarcely leaves any thing to be 

 desired. Nevertheless, as Saint-Hilaire's classification and nomenclature 

 are also employed, and are in some respects advantageous to know, we 

 will now allude to them, though not in such detail as we have done those 

 of Gurlt, and following the summary given by Zundel. Saint-Hilaii^ 

 separates the Monstrosities from the vices of conformation, which he dis- 

 tinguishes as Hemiteries, or simple and trifling organic anomalies, and 

 Ifeterotaxies, or mere changes in the situation of organs, and nearly 

 always without alteration in relative position and connections. For the 

 Hermaphrodisms — due to the union of the sexes or some of their characters 

 in the same individual — he forms a separate class, which he again divides 

 into two subclasses, according as there is an absence or excess in the 

 number of parts ; he distinguishes male hermaphrodism, female her- 



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