The Morphology of Cosmobia 369 



XI. Chicken, newl^y hatched, Diprosopus triophthahiuis, also with 

 four legs, the inner ones smaller. [B. G. Wilder.] 

 XII. Pig, new-born, Diprosopus triophthalmus. | B. G. AVildei!.] 

 XIII. Duck, adult, with a supernumerary leg. [B. G. Wilder.] 

 XIV. Pig, new born (?), two bodies in the form of Omphalopagi, 

 but with a single head with double tongue and lower jaw. 

 [Lambert.] From the Barnum Museum of Tufts College. 

 XV. Lamb, three or four weeks old, with two equal heads. [B. G. 

 Wilder.] Born at Ludlowville, IST. Y. 

 XVI. Chick embiyo, perhaps a "Janus." [Smith College Labora- 

 tory, incubated.] 

 XVII. Kitten, new-born; parasitic thoracopagus. [Mead.] 

 XVIII. Chick embryo, perhaps a "Janus." [Gorham.] 

 XIX. Chick embryo; double primitive streak. [Gorham.] 

 XX. Turtle, small Chrysemys; dicephalus. [Mead.] 

 XXI. Chick, a few days after hatching; double median leg in addi- 

 tion to the normal pair. [Lambert.] 

 XXII. Chick, a few days after hatching; a supernumerary leg upon 



one side. [B. G. Wilder.]^ 

 Of these monsters, which are listed in the order in which they have 

 been received, Xos. VIII, XIII, and XXII are probably not Cosmobia, 

 at least not typical ones, and are hence not considered in any way in the 

 present paper. The others may be placed in groups as follows : — 



A. Janus-Omphalopagus group : Xos. Ill, IV, Y, X, XIV, XVI, 



XVII, XVIII. 



B. Diprosopus gi-oup : Xos. I, II, XI, XII, XV, XIX, XX. 



C. Cyclops group : X"os. VI, VII, IX. 



From this material it is my purpose to select for the use of the pres- 

 ent paper certain topics, the consideration of which may be of direct 

 bearing upon the theory above enunciated rather than to attempt an 

 anatomical description of the several forms, a kind of work of which 



'Since the coiupletion of this paper I have received froui Professor B. (.}. 

 Wilder a large and valuable collection of monsters, which arrived too late 

 for incorporation in this list. One of them, however, Teras XXX. is of such 

 value in this connection that it deserves special mention. This is a kitten 

 embryo of 34 mm., with a partially doubled head, and practically the counter- 

 part of Dr. Lambert's diprosopic pig, Teras T. This I have already sectioned 

 and hope to use it later in connection with further work on Teras I. I am 

 also inserting into this paper a drawing of it in connection with the descrip- 

 tion of this latter monster. (Fig. 271).) 



