DUPLICITY. 5 



in the last preparation. The remains of a single yelk- 

 sac (pseudo -placenta) is seen between the pectoral fins. 



A female Shark was taken by the donor (mate of a vessel) in 

 the Indian Ocean (34 S. lat., 90 E. long.). When brought on 

 deck and cut up, about thirty living young escaped from its abdo- 

 men. The specimen presented lived for two days in a bucket of 

 sea-water. 



Presented by E. Bestard, Esq., 1866. 



Subseries III. IN AMPHIBIA. 



Subclass IV. Heterologous union. 



23. A Frog with a small additional anterior extremity springing 



from the posterior and lateral part of the sternum. 



This preparation has been placed provisionally in its present 

 position, under the theory that the limb in question is the only 

 developed part of a second embryo. Such is probably the case, 

 but there is too little evidence to justify any decided inference. 

 (See also Nos. 47 and 48.) 



Hunterian. 



Subseries IV. IN REPTILES. 



Subclass I. Dichotomy*. 

 A. Anterior Dichotomy.. 



Syn. Cephalodidymi, Gurlt. 



Monstres doubles monosomiens, Geoff: 



24. A small English Snake with two heads. The axis is di- 



stinctly double to about half an inch behind the occipital 

 bone only, although there are traces of duplicity in the 

 ventral region more than an inch further back. 



Hunterian. 



25. A small Snake with two distinct heads and double vertebrae 



in the anterior portion of the body. One head is slightly 

 lateral and smaller ; its neck is shorter than that of the 

 other. Hunterian. 



26. A small Indian Water-Snake (Hydrophis) with two heads. 



Presented by J. Shortt, M.D., 1866. 



* See Introduction. 



