DUPLICITY. 7 



the spinal column. There are four legs and wings. 

 The median wings are united into a single organ. 

 There is considerable deficiency in the coverings of the 

 abdomen. 



35. The posterior part of a Duck affected with slight posterior di- 



chotomy, laid open to show the pelves and their contents. 

 There are four perfect legs, although two only appear to 

 have been functional. The anus is double. That of 

 the right side is imperforate ; it forms a small nipple-like 

 projection externally, and is connected with the cloaca 

 by an imperforate band. The intestine has three caeca 

 instead of two. Presented by Mrs. Robinson, 1819. 



36. The oviduct, rectum, and cloaca of a Fowl with two external 



openings. The cloaca is bifurcated below. A single 

 oviduct opens into its left side. This specimen is pro- 

 bably from a bird affected similarly to the last but to a 

 less degree. Mr. Tegetmeier had a similar Fowl in which 

 both openings were functional. 



Presented by Dr. Halford, 1862. 



37. Posterior dichotomy of the spinal column in a Chick, with 



fusion of the soft parts of the median pairs of legs as far 

 as the knee. Mus. Brit. 



38. A similar Chick. Hunterian. 



39. A Duckling in which there is posterior dichotomy of the 



axis. The left division of the axis is rudimentary in com- 

 parison with the right, and the legs of the left side are 

 fused to the toes. There are two distinct femora and 

 seven digits ; the condition of the limb is similar to that 

 seen in No. 65. This specimen has been partially dis- 

 sected to show the connexion of the redundant limbs with 

 the spine. Mus. Brit. 



40. A Chick with considerable posterior dichotomy of the axis,. 



accompanied with total deficiency of the beak, mandible, 

 and tongue. The posterior nares are completely exposed. 

 The hyoid bone is not deficient. Unfortunately the tho- 

 racic and abdominal parietes have been removed, so that 

 it is impossible to discover how far they were defective. 



41. Posterior dichotomy in a Duckling extending into the cer- 



vical region, and perhaps involving the base of the skull. 

 The neural arch of the skull is open and the brain is 



