of certain Birds of Cuba. 



17 



is constantly 7. In birds on the other hand, of all the ver- 

 tebrae, the cervical vary the most in number ; and indeed, on 

 the length and flexibility of the neck, which in this class are 

 generally produced by an increase in the number of joints, de- 

 pends much of the economy of the species. 



Here then, we first observe that the two Normal groups have 

 the least number of cervical vertebrae, and the three Aberrant 

 the greatest. In the next place, we see that the variation in 

 the number of cervical vertebrae is least in the Raptores, and 

 greatest in the Natatores. Unfortunately, however, the num- 

 bers in two very remarkable genera, Gypogeranus and Tachy- 

 petes*, are not known. The 



* Although this bird has only been of late years well known, the important affinity 

 existing between the Raptores and Natatores was known to Hermann, who says, 

 p. 145 : — " Cataractes genus h. cl. Brunnichio conditum prsecipufe cer& rostri basin 

 tegente differt assimilis hac in re Falconibus. Poterit adeo qui velit cum istis avibus 

 conjungere, et e Falconibus prsecipu^ cum F. leucocephalo, qui simili fer^ mode con- 

 generis Haliati parasitus est : de qua re vid. Catesby, et Cataractem Skuam baud 

 secus ac Falcones rapacem esse terrestremque rapinam exercere et anates gallinas 

 im6 agnos prsedari Sibbaldus, Willughbeius, Brunnichius fidem faciunt." And again, 

 > VOL. XVr. D P- 154, 



