Mr. J. E. Gray on Starfish. 275 



the bone earth (phosphate of lime Ca 8 F 3 ) is the manure, and 

 that this substance only does good in such a soil as is poor in 

 it, which is said not to be the case in Mecklenburg and north- 

 ern Germany, on which account no such astonishing success 

 has been seen to result from manuring with bones. On the 

 contrary, the English soil is said to have been exhausted of 

 its phosphate of lime by the repeated cultivation of wheat, so 

 that in it this manure is very successful. We have shown in 

 the commencement the views which the author takes of the 

 action of mineral substances as manures, and, according to it, 

 the action of several, as lime, marl, gypsum, &c, are explained; 

 if these substances are not present, or are in only small quan- 

 tities in the soil, then they must be added, and in order to 

 ascertain this it is absolutely necessary to examine the soil 

 chemically. If one wishes to manure with marl, both the 

 marl and the soil must be first examined, for marls are very 

 variable in their composition, and it is not every one of them 

 which will suit one particular soil. 



From M. Pabst we have received another very important 

 work on Agricultural CEconomy*, which treats of the cultiva- 

 tion of plants agriculturally, but it is quite practical. He who 

 wishes for any information concerning the cultivation of those 

 domestic plants which can be produced in our country, will 

 find in this work sufficient instruction. 

 [To be continued.] 



XXXII.— -A Synopsis of the Genera and Species of the Class 

 Hypostoma (Asterias, Linnmus). By John Edward Gray, 

 Esq., F.R.S., Keeper of the Zoological Collection in the 

 British Museum. 



[Continued from p. 184.] 



Fam. 3. Pentacerotidje, Gray, Syn. Brit. Mus. 



The body supported by roundish or elongated pieces, covered with 

 a smooth or granular skin, pierced with minute pores between the 

 tubercles. 



A. Pentacerotina. Body pentagonal or suborbicular, rays short, 

 dorsal wart single, the ambulacra edged with a series of small spines 

 divided into rounded groups. 



a. The ambulacra with a single series of large spines near the edge. 



* Body suborbicular, convex above and below ; covered above and 

 below with granules, and scattered conical tubercles. 



* Lehrbuch der Landwirthschaft. Zweiten Bandes. 1" Abtheilung Spe- 

 cielle Productionslehre. Darmstadt, 1839. 



T 2 



