1865.] Zoology and Animal Physiology. 329 



Dr. Humphry, in a conmiunication to the Cambridge Philosophical 

 Society, defends the vertebral theory of the skull on the ground of the 

 constancy of the law of uniformity of plan with variety of detail. It 

 is by all anatomists admitted that the skull is segmentally constructed, 

 and most anatomists are agreed as to the number of the segments. 

 He argues that they should therefore be described by the same name as 

 those of which they are a continuation, since the segmental construc- 

 tion of the skull — the relation of its components to surrounding parts, 

 and so many fundamental resemblances in development, unite to prove 

 that one as well as the other consists of vertebrae modified to meet the 

 requirements of the parts in which they are found. Although, there- 

 fore, Professor Huxley has expressed an opinion that the vertebral 

 hypothesis of the skidl has been abolished by the recent discoveries 

 in development,* Dr. Humphry aflirins, that the greater number of 

 those anatomists to whose observations we are indebted for most of 

 our knowledge of the development of the skull and of the trunk, are 

 agreed that the differences between the mode of formation of the 

 segments in the two form no real argument against the vertebral 

 character of either. 



Professor Peters, in a paper before the Academy of Sciences at 

 Berlin, adds another to the exceptional cases of mammals having more 

 or less than seven cervical vertebras. The only exceptions previously 

 known were the genera Bradypus (Sloth) and Manatus (Manatee). 

 In the former the number varies from eight to ten, and in the latter 

 it is usually six. The example now added by Peters is a species of 

 two-toed sloth, described by him in 1858 under the name of Cholaipus 

 Hofmanni, of which he has received several skeletons, all of which 

 present only six cervical vertebras. 



It is remarked by the natives and old settlers of New Zealand, 

 that many of the native birds are getting scarcer, and a few varieties have 

 all but disappeared. A collector remarks, that of birds which were 

 formerly common he has failed in getting even a single specimen. 

 Early navigators and visitors to New Zealand speak with raptures of 

 the melody of the birds in the woods at early morn. But that the 

 birds are now rapidly disappearing appears certain ; and it is sug- 

 gested that the cause is, the ravages of the common rat. The Bush 

 and country are swarming with them ; they are found in the trees, on 

 the ground, by the water and in the water. Eat life is rampant at 

 the present moment in New Zealand. Birds' nests are found empty 

 everywhere where they ought to have been tenanted, and are almost in- 

 variably robbed by the vermin ; so that a progressive extinction of the 

 native fauna appears to be an inevitable result of the undue increase 

 of that prolific pest, the rat. 



Singing mice have long been known, and the fact of their singing 

 is beyond question, and have supplied the substantial evidence of a 

 good income to the fortunate owners of these musical phenomena. 

 Another well-authenticated instance has occurred at Ashcroft, in Kent, 



* See his recent lectures on Comparative Anatomy. 



