GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA. 1581 



2. The Aucklandian Province, embracing the Aucklands and per- 

 haps the south extremity of New Zealand. 



3. The South Polar province, including the South Shetlands 

 (whence comes the huge Glyptonotus of Eights), and also the Antarctic 

 lands of Wilkes and Ross. 



The group Hymenicinse, including the genera Hymenosoma, Hali- 

 carcinus, and Hymenicus, is peculiarly a southern type, and through 

 these genera the extremities of the continents have a common cha- 

 racter. The first characterizes the Cape of Good Hope, the second 

 Patagonia and Fuegia, and the third New Zealand. The Patagonian 

 genus reaches north to Valparaiso, into the same temperature region 

 (the subtemperate) that affords the Hymenosoma of South Africa and 

 Hymenicus of New Zealand, and this subtemperate region is the 

 highest northern limit of the group. Halicarcinus is developed in its 

 greatest perfection in Fuegia. 



ORIGIN OF THE GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA. 



The origin of the existing distribution of species in this department 

 of zoology deserves attentive consideration. Two great causes are 

 admitted by all, and the important question is, how far the influence of 

 each has extended. The first, is original local creations; the second, 

 migration. 



Under the first head, we may refer much that we have already said 

 on the influence of temperature, and the restriction of species to par- 

 ticular temperature regions. It is not doubted that the species have 

 been created in regions for which they are especially fitted ; that their 

 fitness for these regions involves an adaptation of structure thereto, 

 and upon this adaptation, their characteristics as species depend. 

 These characteristics are of no climatal origin. They are the impress 

 of the Creator's hand, when the species had their first existence in 

 those regions calculated to respond to their necessities. 



The following questions come up under this general head : — 



1. Have there been local centres of creation, from which groups of 

 species have gone forth by migration ? 



2. Have genera only and not species, or have species, been repeated 

 by creation in distinct and distant regions ? 



3. How closely may we recognise in climatal and other physical 



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