August 30, 1895.] 



SCIENCE. 



273 



enee of the American genera Philodryas and 

 Heterodon among snakes, a fact which is remark- 

 ably paralleled by the Centetidie among the 

 Insectivora" (189). The Madagascar snakes 

 are differentiated generically and belong to 

 different groiips from the American species, and 

 the Centetidas belong even to a family differing 

 fi'om the American forms (Solenodontidte) with 

 which they have been associated. 



Mr. Beddard's work is very suggestive and 

 leads to so many questions of interest that it is 

 with difiiculty we can circumscribe our inquiries 

 within the limits of a review. We can only 

 touch upon a few points of interest. 



Although the only class groups systematically 

 considered by Mr. Beddard are the mammals 

 and birds, he has introduced a number of sec- 

 tions treating of the distribution of various 

 minor groups, as the edentates, cuckoos, tor- 

 toises, lizards, crocodiles, snakes, batrachians, 

 scorpions and earthworms. The section on the 

 earthworms is especially valuable, as it contains 

 the results of Mr. Beddard's most recent investi- 

 gation of a group of which he has made a special 

 study and quite lately published a monograph. 



Mr. Beddard very properly remarks that 

 ' ' Land Mollusca would appear on many grounds 

 to be exceedingly valuable as furnishing evi- 

 dence in favour of ancient land connections ' ' 

 (p. 83), hut then quotes Mr. Blanford in opposi- 

 tion. Eecent niOlacologists, and above all Prof. 

 Pilsbry, have done much to correlate the data 

 of structure and distribution. We feel inclined 

 here to take exception to the statement re-echo- 

 ing the old idea of ' the existing genera Pupa 

 and Zonites going back to carboniferous times ' 

 (p. 85). The carboniferous species referred to 

 those genera are certainly much like the recent 

 species, but it must be remembered that shells 

 having the same contours are secreted by animals 

 quite dissimilar in anatomical features. The pre- 

 sumption is entirely against the generic identity 

 of the ancient and modern forms, and Dendropu- 

 pa (Owen, 1862) is a name proposed for the old 

 upiform shells. Nevertheless the groups of mol- 

 lusks are very long lived, and their presence in 

 a country has a significance quite different ft'om 

 that of a mammal or other vertebrate. This 

 may be well understood when we recall that 

 almost all of the modern families of mollusks 



originated before the commencement of the ter- 

 tiary period, while almost none of the families of 

 mammals came into existence until long after. 

 The correlated fact follows that few families or 

 even genera of mollusks are circumscribed in 

 their distribution like so many of the vertebrates. 



Mr. Beddard, in his systematic sketches of the 

 various regions of the globe, has added lists of 

 ' families ' and ' genera ' supposed to be ' peculiar 

 to ' those regions, but sometimes without sufli- 

 cient reason. For example, of ' genera confined 

 to the [Palearetic] region ' (p. 89), Anurosorex 

 also occurs in the oriental region (Assam), Bos, 

 however restricted, in the oriental region at 

 least ; Capra in ' the Neilgherries and some other 

 ranges of southern India ' (p. 22), and Ferisoreus, 

 Cyanocitta, Nucifraga and Acanthis are common 

 in North America. Indeed Cyanocitta is exclu- 

 sively North American, and must have been in- 

 troduced into the present list through some mis- 

 take. The lists of the families and genera peculiar 

 to the ' Neoarctic region,' as well as to the ' Neo- 

 tropical region,' require still more revision and 

 large additions which space forbids us to under- 

 take. In view of the fact that many peculiar 

 South Ajnerican genera have been omitted, we 

 are rather surprised to find Tomes' almost forgot- 

 ten Hyracodon (1863) resuscitated as a ' peculiar ' 

 genus of Neotropical marsupials (108). Tomes' 

 genus may possibly have been based on a young 

 Didelphys, although the characters assigned 

 scarcely seem to be applicable to such ; it has 

 even been overlooked by Thomas, but in any 

 even the name Hyracodon cannot be used, as it 

 had been taken previously by Leidy for a well- 

 known extinct genus related to the rhinoceroses. 



Because animals are found between certain 

 degrees of latitude, it does not follow that they 

 specially affect the temperatures prevalent in 

 the lowlands of such countries. The humming 

 birds may be more numerous in tropical lands, 

 but many types are confined to mountains and 

 occur about the summits of very high ones 

 and consequently in cold regions. Mr. Beddard 

 says that ' ' it upsets the current notions as to 

 the tropical habits of the humming birds to 

 learn that a species, Selasphorus mfus, breeds in 

 Alaska " (p. 97), but the well-known facts as to 

 the elevations where humming birds occur and 

 as to the extension of species into the still 



