182 THE CANADIAN NATURALIST. [Vol. vil* 



not accumulate in limestone regions, but that the peat mosses of 

 such regions all belong to the genus Hjpnum. I have found no 

 other moss entering into the composition of Iowa peat. 



Another fact observed in this connection has doubtless much 

 significance, namely, the Ericaceae are almost entirely wanting in 

 Iowa, and no plants of that order have yet been observed by 

 myself in or about these Hypnum marshes. The principal plant 

 assisting the Hypnum in the production of peat is a kind o^ 

 grass. 



Should one go north from Iowa or Illinois into the metamorphic 

 regions of Minnesota and Wisconsin, I think he would see the 

 Hypnum gradually give place to Sphagnum in the marshes, and 

 the marsh Ericaceae appear with the last named moss. 



In short, lime seems to be an uncongenial element in the habi- 

 tat of both Sphagnum and most if not all ericaceous plants, but 

 is not uncongenial to Hypnum and grass. Therefore the abun- 

 dant presence of lime will not necessarily prevent the accumula- 

 tion of peat. — Ihid. 



Circulation in the King Crab. — M. Alphonse Milne- 

 Edwards finds that the circulating apparatus of Limulus is more 

 perfect and complicated than that of any other articulate animal. 

 The venous blood, instead of being diffused through interorganic 

 lacunae, as in the Crustacea, is, for a considerable portion of its 

 course, enclosed in proper vessels with walls perfectly distinct 

 from the adjacent organs, originating frequently by ramifications 

 of remarkable delicacy, aod opening into reservoirs which are 

 for the most part well circumbscribed. The nutritive liquid 

 passes from these reservoirs into the branchiae, and, after having 

 traversed these respiratory organs, arrives by a system of branchio- 

 cardiac canals, in a pericardiac chamber, then penetrates into the 

 heart, of which the dimensions are very considerable. It is then 

 driven into tubular arteries with resistant walls, the arrangement 

 of which is exceedingly complex, with frequent anastomoses, and 

 of which the terminal ramifications are of marvellous tenuity and 

 abundance. He has also found, as Prof. Owen had intimated, 

 that the nerves are completely ensheathed by the blood vessels. 

 — Annals and Mag. Nat. History. 



In the Chronique de la Societe d'AccUmatation, M. Ruimet 

 states that by feeding silk-worms on vine-leaves he has obtained 



