Miscellaneous, 359 



narrowed into an elongated peduncle ; and if this is broken, the little 

 creature moves freely in the water by movements of its body. No 

 vibratile apparatus could be detected. 



The author says that these bodies cannot be parasites, on account 

 of the continuity of their tissues with those of the animal ; and he 

 does not think they can be regarded as oculiferous tentacles, because 

 great mobility of the eyes occurs only where those organs are very 

 few in number. — Comptes Rendus, February 27, 1865, p. 441. 



On the Normal Occurrence of only Six Cervical Vertehrce in Choloepus 

 Hoffmanni, Peters. By Professor Peters. 



As a general rule, all the Mammalia have seven cervical vertebrae, 

 the only known exceptions to this rule being found in the genera 

 Bradypus and Trichechus^ Linn. (Manatus, Cuv.). The species of 

 the former usually have nine cervical vertebrae, rarely eight* or ten. 

 In the latter the normal number is sice. 



In 1858 the author described a new species of two-toed Sloth 

 from Costa Rica, under the name of Choloepus Hoffmanni \\ and he 

 has since received perfect and imperfect skeletons of this species which 

 present a second example of the occurrence of six cervical vertebrae 

 among Mammalia, and at the same time furnish an additional cha- 

 racter for the distinction of this short-toed species from the long- 

 toed C. didactylus from the north of Brazil and Guiana, which has 

 the normal number of seven vertebrae in the neck. 



The total number of vertebrae is forty- six in five of the skeletons ; 

 in a sixth, very young specimen, the last caudal vertebrae have been 

 cut away. All of them have only six cervical vertebrae. Of these 

 skeletons, four have all the cervical vertebrae separate ; one has the 

 second and third vertebrae anchylosed together, as observed by A. 

 Wagner ;j; in C. didactylus ; and one presents, in addition to this, an 

 anchylosis of the sixth cervical with the first dorsal vertebra. Four 

 skeletons have 23 dorsal vertebrae and pairs of ribs, 3 lumbar and 8 

 sacral vertebrae ; one has 23 dorsal, 4 lumbar, and 7 sacral vertebrae ; 

 and one exhibits 24 dorsal vertebrae and pairs of ribs, only 2 lumbar 

 vertebrae (the first lumbar being reckoned as dorsal, from its having 

 ribs), and 8 sacral vertebrae. All, with the exception of the damaged 

 young animal, have 6 caudal vertebrae, of which the last two are 

 anchylosed in one specimen. 



Throughout the Sloths there appears to be a great tendency to 

 the formation and anchylosis of bones. To the observations already 

 recorded upon this subject the author 'adds that sometimes in Bra- 

 dypus {tridactylus) the hyoid bone and its cornua are amalgamated 



* This number occurs generally in Bradypus torquatus, which may be 

 regarded as the type of a distinct genus, on account of differences in the 

 form of the skull, hyoid bone, and humerus : for this, if established. Pro- 

 fessor Peters proposes the name of Sceeopus. 



t Monatsber. Berl. Acad. 1858, p. 128. 



i Schreber's ' Saugethiere,' Supplement iv. p. 155. 



