Source of Carbon and Nitrogen in Plants and Animals. 369 



It may appear an homely comparison, but, to liken small things with 

 great, the analogy is complete, between the arrangements of nature, in 

 supplj'ing from below the gaseous materials which the crop requires for 

 its growth, and the plan often adopted by the gardener, of placing in a 

 vessel, underneath the roots of a plant, a body of animal manure, which, 

 by its exhalations, communicates to it the very same principles. 



Should these views receive credence, and obtain confirmation from 

 future investigations, they will afford a proof that geology, no less than 

 the sister sciences of chemistry and vegetable physiology, is capable of 

 throwing light upon questions in which the agriculturist is concerned — 

 but of this truth it would indeed have been needless to search for proofs 

 in countries so distant, or by an appeal to phenomena with which the 

 English farmer is happily unacquainted; since we shall have abundant 

 opportunities in the course of these lectures of shewing, that it will be 

 brought home to him bj T facts of which he has daily experience, and 

 which present themselves to his notice in the common business of life; 

 for, if it be the office of the chemist to explain the causes of those differ- 

 ences which exist between soils, and the means of improving them by 

 manures, it is no less that of the geologist to point out where those of 

 the best description are to be met with, what resources we have at hand 

 in the bowels of the earth underneath, or in the contiguous strata, for 

 remedying their defect, and what facilities for drainage, and other methods 

 of amelioration, the physical structure of the country may chance to 

 supply. 



On the Natural History and Anatomy of Thalassema and 

 Echiurus. By Edward Forbes, Esq. and John Goodsir, 

 Esq. Members of the Wernerian Natural History Society. 

 With a Plate. (PL VII.) (Communicated by the Authors.)* 



Amoxg the Radiata of the British seas are two animals 

 which, in their general appearance, rather resemble Annclides 

 than Echinodermala, to which latter class they structurally 

 belong'. These are the Thalassema Neptuni and Echiurus 

 vulgaris, members of the family Thalassemacecu in the order 

 Sipunculidce, a zoological and anatomical description of which 

 species we have to-day the pleasure of submitting to the Wer- 

 nerian Society. 



The family Thalassemacecv includes a group of vermigrade 

 Echinodermata, characterized by having cylindrical worm- 



* Read before the Wornerian Natural History Society on 23d January 

 1841. 



