404 Duplicate Twins and Double Monsters 



&. Like (a) hut united from the shoulder doionwards and with a median 

 anterior limb, or limb-rudiment, and no median leg. 



Type: Barkow's case, cited by Fisher, 66. 



The two components were united from pelvis to shoulder, and were appar- 

 ently single below the waist, with a single pair of legs. In place of two 

 median arms, such as are seen in the cases under (d), a median bilateral 

 member appears, attached to what is apparently a double shoulder girdle, 

 formed of equal contributions from the two components. A sketch is given of 

 the bones of this median limb, which shows an abnormally broad humerus, 

 to which are articulated a median ulna (double) and two radii, laterally 

 placed. The digits are ten in number, not palm and palm, as in Fenn's fetus 

 above, but side by side, the ulnar sides at the median line (Fig. 4, c and d) . 



Other cases: 



1. Gurlt's double calf (copied from Gurlt's Atlas by Fisher, Fig. 5). 

 This is so similar to the last that a detailed description is unnecessary. 



The duplication extended, however, farther down the back and there seemed 

 to be two nearly complete vertebral coluqins and two tails. 



2. Meckel's fetus. Carefully dissected, described and figured in a large 



folio, published 1815. 

 The inner arms are represented by a median rudiment which proceeds from 

 a double shoulder girdle. The rudiment consists of two joints called humerus 

 and antebrachius by the author. 



3. Gruber's fetus (1859, " Thoracogastrodidymus I"), is of great interest 



here since it is like that of Meckel (2), except that the median 

 arm rudiment is considerably smaller. There is but a step between 

 this and the " Thoracogastrodidymus, Case II," of the same author, 

 described below. 



4. Zimmer's " Dicephalus tribrachius,'" figured by Forster, 6i, in Taf. VI, 



Fig. 4, evidently belongs here. The fact that the left component 

 suffers from other defects is plainly a mere coincidence, without 

 significance in our present study. 



c. Forms which, like (a) and (b), consist of two laterally united compo- 

 nents, but with a median double limb, or limb-rudiment, from both anterior 

 and posterior limb-regions. 



Type: Fenn's fetus; described by J. Wyman; specimen in Harvard Medical 

 School (Fisher, 66, pp. 276 f£.). 



This is the best case of all to illustrate the real double composition of 

 these median appendages, since neither the arm nor the leg is really rudi- 

 mentary but both are of perfectly bilateral symmetry and show the two equal 

 components which, had the anlagen separated a little more, might each have 

 formed two separate and perfect members. 



As this is so important a case, a rough tracing of Fisher's plate, with a 

 detail of the median foot, is here presented (Fig. 4, a and b) . The description 

 of the median appendages is as follows: The arm is double and symmetrical, 

 and the foot is " compound and provided with two groups of toes, of three 

 each, one right and the other left, and a single large symmetrical toe arose 

 from the middle of the back of the foot. This toe had a nail on each side " 

 (Fisher). 



