100 



May 8, 1832. 

 W. Yarrell, Esq. in the Chair. 



A preparation was exliibited of the generative organs of a hybrid 

 malė bird, bred by the Society, and produced between a Muscovy 

 Drake and a commoii Duck; and Mr. Yarrell described the external 

 and internal appearances of the individual from vvhich the prepara- 

 tion was obtained. 



He stated that the bird in its plumage, with the exception of a 

 small chestnut-coloured patch on the chest, exhibited all the ap- 

 pearance of a true Muscovy Drake, The head, neck, back and wings 

 were marked vvith the purple and violet tints vvhich usually charac- 

 terize that species; the curled feathers at the base of the tail, pecu- 

 liar to the malęs of Anas Doschas, were wanting. 



Internally the viscera generally partook more of the character of 

 Anas Boschas, but particularly in the length of the intestines and 

 caecal appendages, which are remarkable for their variation in this 

 respect, depending on the species, and having a due relation to the 

 nature of the food selected by each. The organ of voice, a most 

 valuable cricerion of species throughout this numerous family, was 

 in its form much more likę that of Anas Boschas than that of Anas 

 moschata, the bony enlargement being nearly globular, without any 

 of the depression uhich is constant in this part in Anas moschata. 



All the parts of the sexual organs were of large size, and appa- 

 rently perfect. 



Mr. Yarrell concluded by remarking that the hybrid bird in ques- 

 tion strongly resembled the true Muscovy, while internally the 

 viscera were as decidedly indicative of the common, Duck. 



The Skeletons of Capromys Fournieri, Desm., and Dasyprocta 

 Acouchy, F. Cuv., having been placed on the table, Mr. Owen en- 

 tered into a series of remarks explanatory of their peculiarities, 

 vvhich he pointed out vvith reference to the skeletons of other Rodentia 

 exhibited for the purpose of comparison. He showed that the 

 cranium both in Capromys and in the Acouchy presents a gentie 

 curve along the coronal aspect, and that this surface is bounded 

 by nearly parallel lines, as in the Agouti and Capybara, difFering 

 from that of Arvicola, Mus, HypudcBus, Bathyergus, and many other 

 Rodentia, in which the frontai bones are more or less compressed 

 between the orbits. The orblts are more circumscribed by bone 

 than in the Rat, in consequence of the developement of the post- 

 orbital process. The Acouchy, however, resembles the Rat in the 

 slenderness of the zygomatic arch ; whilst Capromys has this arch 

 broad and strong, as it exists in Hystrix, Castor, Lepus, and Capy- 

 bara, although it is far from presenting the enormous developement 

 cxl)ibited in Ccelogenus, The suborbital ybra»»wa, though larger 



