ZOOLOGY. 841 



continuous (approximatively) in a zone round its surface, it is clear 

 that there must be some such general agreement. 



Now, Prof. Fdrbes finds that if we lay down the marine provinces 

 according to the knowledge we have of the distribution of species, the 

 lines bounding such provinces latitudinally may be connected across 

 the land by lines which, in the main, correspond with the great fea- 

 tures of the arrangement of terrestrial vegetation and animal life. In 

 general the lines on land are drawn in accordance with the isothermal 

 of the month in which the greatest development of animal and vege- 

 table life taken together is manifested within the region. By " great- 

 est development" of life, Prof. Forbes means that the greatest number 

 of vertebrata and articulata are out and active at the same time, and 

 the greatest number of plants are in flower phenomena which are 

 co-existent. To the zones included between the lines thus drawn 

 the Professor gives the name of homoiozoic belts. From north to 

 south such a belt corresponds with only a single province, but from 

 east to west it may include several. The various provinces included 

 within any given belt, if they are geographically approximated, resem- 

 ble one another in consequence of the identity of many of their species ; 

 but if they are geographically distant, the resemblance consists in the 

 representation of species of the one by species of the other. Nine 

 homoiozoic belts are to be distinguished, one of which is central and 

 equatorial, and the other eight are contained, four in the northern, and 

 four in the southern hemisphere. These belts are: 1. The north 

 polar homoiozoic belt ; its southern limit corresponds very nearly with 

 the isotherm of 54 5' in the month of June in Dove's map. It 

 includes only the arctic province. 2. The north circumpolar homoio- 

 zoic belt ; its southern limit (exclusive of the British area) answers 

 nearly to the isotherm of 59 in June. It contains the Boreal, Sitch- 

 ian, and Ochotyian provinces, which are wholly representative, any 

 identical species being derived from the arctic province. 3. The 

 northern neutral homoiozoic belt, whose southern limit is the isotherm 

 of 63 in June, and 68 in July. It comprehends the Celtic and 

 Virginian, and the Mantchourian and Oregonian provinces. The 

 Celtic and Virginian provinces represent one another, as also proba- 

 bly do the Mantchourian and Oregonian. 4. The northern circum- 

 central homoiozoic belt has the isotherm of 68 in May for its southern 

 limit. It contains six provinces, the Lusitanian, Carolinian, Mediter- 

 ranean, Japonian, Caliibrnian, and Aralo-Caspian. 5. The central 

 homoiozoic belt contains the West African, Caribbean, and Panamian 

 areas, besides the largest of all marine provinces, the Indo-Pacific. 6. 

 The southern circumcentral homoiozoic belt is limited northward by 

 the isotherm of 68 in October, though this does not quite exactly 

 coincide with its marine boundary. It represents very forcibly the 

 northern circumcentral belt, and contains the Peruvian, Urugavian, 

 South African, and Australian marine provinces. 7. The southern 

 neutral homoiozoic belt, limited by the isotherm of 59 in January, 

 contains the east Patagonian and Araucanian provinces. 8. The 

 southern circumpolar homoiozoic belt has for its northern limit the 



