134 Bibliographical Notices. 



Leskia. Shell ovate, siibglobose, thin, vertex central ; lateral 

 ambulacra broad, petaloid, rather sunken and separate from each 

 other, the hinder lateral pair father the shortest, the odd anterior 

 ambulacra in a rather broad sunken groove, rudimentary, with 

 only a single series of pores on each side; all sun*ounded by a broad 

 rather sinuous peripetalous fascicle ; lateral and subanal fasciole 

 none ; mouth anterior, round, on a level with the rounded under 

 surface, and covered with five triangular converging valves ; 

 plastron and subanal plate not distinctly defined ; anus round, in 

 the upper part of the rounded posterior end, and covered with 

 five triangular converging valves forming a cone, with some small 

 spicula in the centre ; ovarian pores two, very large j spines and 

 tubercles subequal, subulate, those of the back being rather the 

 largest. 



This genus agrees with Brissus in the form of the peripetalous 

 fasciole, but difi'ers from it and all the other Spatangid<E in the 

 form of the mouth and vent. 



1. Leskia mirabilis. Shell ovate, subglobose. 

 Hab. Isle of Luzon. 



BIBLIOGRAPHICAL NOTICES. 



The Dynamical Theory of the Earth. By Archibald Tucker 

 Ritchie. Longmans, London, 1850. Vol. i. pp. 562 ; vol. ii. 

 pp. 664. 



Cosmogonies seem to have shared the fate of the philosopher's 

 stone, the perpetual motion, and such other dreams. Given up by 

 the true philosopher, such projects have become at once the glory 

 and the stumbling-block of those who with much learning and little 

 knowledge seek at the well of truth, diligently indeed, but who, like 

 scientific Danaiides, seem condemned to draw the living waters with 

 a sieve. 



The many-sided man of science, skilled at once in books and things, 

 whose wide ken scans the whole field of human knowledge, modestly 

 confesses a cosmology to be beyond his powers, and contents himself 

 with a mere " Cosmos," — a statement of what the world is, not how it 

 came to be : and where Humboldt feared to tread, the author of the 

 ' Vestiges of the Creation,' and Mr. Ritcliie in the present work have 

 rushed in. 



We have mentioned these two works together, but we would not 

 do the ' Vestiges ' the wrong to say, that it is from any similarity 

 between them : truth to say, their relation is one of antithesis, not of 

 resemblance. 



The style of the ' Vestiges ' is alwaj's grammatical and eminently 

 perspicuous, sometimes indeed rising to eloquence. The style of the 

 ' Dynamical Theory ' is frequently ungrammatical, rarely perspicuous, 

 and often descends to twaddle. 



