1878.] Recent Literature. : 385 
Again, the Arachnida are placed in a division with “ pediform 
Gnathites,” but in what respect are the mandibles and maxille of 
spiders and mites any more pediform than those of insects and 
Myriopods? And in the sucking Myriopods we have an entire 
family with mouth parts not much higher in grade than those of 
the Tardigrades and Pentastomida. 
The author shows a tendency to coin terms for parts already 
named, thus goxapophysis is used instead of Lacaze Duthier’s 
elegant term rhaéddite for the blades of the ovipositor. The term 
Echinopedium is used for the larva of Echinoderms, which. 
exactly corresponds to Packard’s Cephalula, proposed in this 
journal (May, 1875, p. 283, and Life Histories, p. 94) and extended 
to embrace a similar phase in molluscs and worms, as well 
Echinoderms. But these are the merest blemishes in a work 
quite indispensible to students, and the production of one whose 
general accuracy of statement is universally recognized. 
Hunt’s CHEMICAL AND GEOLOGICAL Essays.! — No changes 
appear to have been made in the text beyond the correction of 
typographical errors, but in the preface to the second edition, 
Prof. Hunt takes the opportunity to farther notice the question of | 
the temperature of the earth’s surface in former geological periods. 
He concludes that a reduction in the weight of the atmosphere 
in early geological times, by causes to which he alludes, must 
have produced a considerable refrigeration of climate, and a still 
greater cooling of the globe by the diminution of the proportion 
of carbonic dioxyd contained in the atmosphere. He concludes 
as follows: “ Geographic changes, though a true cause of local 
variations of climate, and adequate to explain the greater refriger- 
ation of certain areas since the commencement of the pliocene, 
are not sufficient to account for the warmer climates of previous 
southern hemisphere lead them to similar conclusions. The nur- 
series of these successive northern floras appears to have been in 
irregular periods, a cooler climate in the northern temperate zone. 
1 Chemical and Geological Essays. By THOMAS STERRY HUNT, LL.D., etc. Sec- : i 
ond edition. Revised, with additions. Salem, S. E. Cassino, Naturalist’s Agency. 
1878. 12mo, pp. 489. _ fs o : u a 
