322 Geographical Distribution of Crustacea. 
The Lithodea belong to the coldest temperate regions, abound- 
ing especially in the subfrigid region. The Galatheidea are 
mainly of the temperate zone; there are five known torrid spe- 
cies, and seven temperate, the latter pertaining to the colder seas. 
The genus Porcellana has but two-thirds as many species in 
the temperate as in the torrid zone. Yet the subtemperate region 
contains but one less than the subtorrid, and some of the largest 
species of the genus occur here; while, on the contrary, the 
torrid-zone species are quite small. Although, therefore, Porcel- 
Jana may rank as a torrid zone genus, if we consider the relative 
number of species in the two zones, it is more properly a tem- 
perate zone genus. — 
‘The Paguridea range through both the tropics and temperate 
zone, even passing into the frigid zone. Bernhardus is mainly 
a cold-water genus, while Pagurus, Calcinus, and Clibanarius are 
mostly torrid genera. Pagurus has seven out of twenty-one 
Species in the temperate zone. But it is in the torrid zone where 
the species of the largest size occur; the extra-torrid species be- 
long almost exclusively to the Mediterranean. The species are 
temperate zone. : 
Among the Paguridea, the Bernhardi or cold-water species are 
probably the superior in rank; and the Lithodea, which are a 
grade higher still, are from the neighborhood of the frigid zone. 
The Hippidea, which we have considered as in the Corystoid 
series, but below the Corystoidea, are mostly from warmer waters. 
The most bulky forms among the Anomoura are found 1n the 
genera Lithodes, Ranina, and Dromia. ‘he common /tanmé 
dentata has a length of five inches in the Japan Seas, while 10 
