MISCELLANEOUS NOTES. 387 



exhibited as such by this fraternity are usually the earth snakes, creatures 

 remarkable among their kind for the bluntness of their tails, a condition 

 which lends itself peculiarly well to the artifices of these people, who mutilate 

 or otherwise modify them so as to make them resemble the head. The snake 

 usually selected for this purpose, both on account of its abundance and size, is 

 John's Earth Snake {Eryx jolinii). 



It is perhaps not so well-known that genuine double-headed snakes do occur 

 occasionally as freaks, but in these instances both heads are always attached 

 to the anterior extremity of the body constituting what is technically called 

 anterior dichotomy. 



Dichotomy (Greek dicha in two parts, temno I cut) arises from a cleavage 

 of one or other pole of the developing embryo, and may occur anteriorly or 

 posteriorly. It may be partial when the reduplicated heads, sterns, or bodies 

 remain more or less attached to one another, or complete when two separate 

 organisms are derived, so that this phenomenon accounts for one method by 

 which twins are produced. There are abundant examples of monstrosities in 

 man and the lower animals formed by this process to be found in various 

 museums, and it is therefore not surprising that the same abnormality occurs 

 occasionally in snakes. 



I have just had an opportunity of examining a young specimen of the 

 common Lycodon aulicus exhibiting this anomaly, which I found on the 

 shelves of the Fyzabad Museum. This specimen has the head and neck 

 reduplicated, and a reference to my notebook shows that all the records of 

 this peculiarity I have been able to collect from various sources, are examples 

 of anterior dichotomy. I have never heard of an example of posterior dicho- 

 tomy in snakes, though the condition doubtless occurs, and has been observed 

 in frogs and other reptiles. This Fyzabad specimen, which measures a shade 

 over 5| inches, is evidently a hatchling. The dual nature of the head and neck 

 is very evident to sight and touch for f of an inch. The reduplicated parts 

 are placed side by side, and are connected by a web except for ^ of an inch 

 where the snouts are quite free. The web commences opposite the 8th supra- 

 labial shields, and is placed rather nearer the ventral aspect, so that the chins are 

 approximated. At the point where the two necks blend, is a pronounced 

 rounded dorsal prominence. The size and sodden condition of the specimen 

 render the detail of the scale characters somewhat difficult to determine with 

 accuracy ; however, I have made the following observations : — The prseocular 

 touches the frontal shield on the right side of the left head only. The rows of 

 scales anterior to the dorsal prominence, i.e., over the cleft part of the body, are 

 variable, but number about 27 ; behind this they are the normal 17. There are 

 189 ventrals, those beneath the bifurcated parts are not double, but extend 

 completely across both trunks. The navel implicates the 167th and 168th 

 shields so that 21 intervene between it and the anal shield, which is divided. 

 The subcaudals are 62. In other respects the scales and shields are normal. 



The following from my notebook may add to the interest of this note. 



