1848.] 



27 



Total length of skin, from lip of bill to end of tail about 12^ inches, wing 



G-3-. inches, tail G;^ inches. 

 10-. 

 HvB. South America. 



This species, of which one specimen in the Rivoli collection is now described, 



is remarkable for the uniform colour of its plumage, in which respect it differs 



from any other species known to me. It is, however, more nearly related to 



C. viridkyanus {D' Orb.) C. ornaius (Lfss.) and C. urmillutus (G. ]\ Gray,) 



than to any others, from which I infer that it is, in common with those beautiful 



species, an inhabitant of the northern part of South America. 



The Committee on Dr. Leidy's paper, entitled " On certain bodies 

 resembling the Pacinian corpuscles in the Boa constrictor," reported in 

 favour of publication. 



On some bodies in the Boa Constrictor resemlling tlue Faciman ccrpiiscles. 



By Joseph Leidy, M. D. 



While engaged with my friend, Dr. Hallowell, a few weeks since, in dissecting 

 the specimen of Boa constrictor presented to the Academy by Dr. Watson, I 

 observed along the course of the nervi intercostales, at or towards their anterior 

 extremity, a number of small, hard, rounded, or ovoid bodies, which, to the 

 naked eye, had very much the appearance of the corpuscula Pacini of man and 

 other mammifera, and such an opinion I expressed at the time to Dr. Hallowell. 



These bodies average from three to seven in number to each nerve, and 

 generally measure eight millemetres in diameter. They are white, shining, and 

 opalescent in appearance, and are closely attached to the side of the nerve, • 

 enclosed within its sheath and projecting beyond its outline, instead of being 

 attached to a pedicle derived from an adjacent nerve, as in the Pacinian corpuscle 

 of man. 



Upon investigating the structure of these bodies through the aid of the micro- 

 scope, I find that they consist of a central, globular mass, measuring .33 mille- 

 metres in diameter, invested by a series of semitransparent capsules in the neigh- 

 borhood of fifty in number. 



The central mass is semi-opaque, homogeneous, granular in structure, slightly 

 yellowish in colour, and has in most cases a darker and more consistent nucleus 

 having apparently the same composition. Acetic acid had almost no influence 

 upon it. With the greatest care, and the use of the highest powers of the micro- 

 scope, I could discern nothing more than a finely granular constitution in it. A 

 somewhat analogous appearance I have noticed in the nervous structure in the 

 interior of the Pacinian corpuscle of the new-born child. 



The capsules enclosing the central mass form a stratum of the same or one- 

 third greater diameter; they are perfectly distinct from one another, are further 

 separated by the endosmosis of fluid, and have the same appearance as those of 

 the Pacinian corpuscle of man. Evidently fibrous, or composed of the white 

 fibrous element, they are rendered quite translucent by the application of acetic 

 acid. Situated upon their inner surface, at nearly regular distances from one 

 another, are situated projecting, elongated oval, or fusiform, a few sigmoid, gran- 

 ular nuclei, larger than those of the Pacinian corpuscle of man, and measuring 

 .025 mil. in length, by .0075 mil. in breadth. 



The outermost capsules become blended with the white fibrous tissue, forming 

 the sheath of the nerve. No nerve fibril passes into the interior of these bodies, 

 although from their great resemblance to the Pacinian corpuscle I had expected to 



