SPA 



[410] 



S P E 



SPATA'NGUS. A genus of echini^ of 

 the section Cor marinum, belonging 

 to the class Pleurocysti. It is 

 characterised by the bilabiated 

 mouth being in the third region of 

 the axis of tho base, and the anus 

 in the side of the truncated ex- 

 tremity. There are a great many 

 species of the genus. The shell of 

 the spatangus is oval, possessing 

 a great number of spines, by the 

 action of which it buries itself in 

 the sand. Fossil spatangi are very 

 abundant in the chalk formation. 



SPATHE. (spatTia, Lat.) In botany, 

 a kind of bractea ; a large coloured 

 bractea which envelopes the princi- 

 pal axis of sessile flowers ; it forms 

 a sort of hood or sheath, opening 

 longitudinally, at some distance 

 from the flower ; the arum, calla, 

 &c. are examples. 



SPA'THIC. In mineralogy, lamellar ; 

 foliated. 



SPA'TTTLATE. 



1. In botany, applied to leaves 

 shaped like a spatula or battledore, 

 having the upper part of a roundish 

 figure, the base tapering and 

 linear. 



2. In conchology, applied to shells 

 which are rounded and broad at 

 the top, and becoming narrower 

 below. 



3. In entomology, applied to the 

 figure of insects, when commencing 

 with a narrow base, gradually 

 widening by the lateral margins 

 sloping out, and terminated at the 

 extremity by a sudden straight 

 line. 



SPE'CTES. (species, Lat.) 



1. That which is predicated of 

 many things as the whole of their 

 essence. 



2. In mineralogy, a species may 

 be defined, a collection of minerals, 

 which ^ are composed of the same 

 ingredients, and combined in the 

 same proportions. 



3. In entomology, a group of 

 natural bodies which agree together 



in all their essential, unchangeable 

 characters. The idea of species 

 comprises in it a congruency, that 

 is to say, not a mere conformity, 

 but also a resemblance of its indi- 

 viduals. Species is the lowest of 

 all the systematic groups, and con- 

 sequently, the most fixed and 

 conformable. 



4. In botany, according to Jussieu 

 and others, a species is a combi- 

 nation of individuals alike in all 

 their parts. De Candolle makes it 

 " a collection of all the individuals 

 which resemble each other more 

 than they resemble any thing else ; 

 which can by mutual fecundation 

 produce other individuals; and 

 which reproduce themselves, by 

 generation, in such a manner that 

 we may from analogy suppose them 

 all sprung originally from one 

 single individual." 



"What is a species? has long 

 been a questio vexata among biolo- 

 gists. If, however, we adopt the 

 idea of a species being the descen- 

 dants of a single pair, successive 

 generations of their species being 

 possible among those descendants, 

 and them only, we shall find the 

 facts of the distribution of species 

 harmonize well with this idea." 

 Jukes. 



SPEC'IFIC GRA'VITY. As this is a term 

 extremely common and in constant 

 use in mineralogy, it may be de- 

 sirable to define it. " The specific 

 gravity of a body is its weight, 

 compared with that of another 

 body of the same magnitude. Thus, 

 if a cubic foot of water weigh 1000 

 ounces, and a cubic foot of iron 

 7000 ounces, their comparative 

 weights or specific gravity are as 

 1000 : 7000, or as 100 : 700 or as 

 10 : 70, or as 1 : 7." Phillips. 



SPHA'GNOUS. Mossy. 



SPE'ETON CLAY. A member of the 

 Lower Cretaceous or Neocomian 

 series. Its exact position is re- 

 garded as still uncertain. Prof. 



