SPA 



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SPATA'NGUS. A genus of echini, of the 

 section Cor marinum, belonging to the 

 class Pleurocysti. It is characterized by 

 the bilabiated mouth being in the third 

 region of the axis of the 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. 

 Dr. Mantell enumerates four species 

 found in the chalk, one species found in 

 thfr chalk marl, and one iu the upper 

 green-sand. 



SPATHE. (spatha, Lat.) In botany, a kind 

 of bractea ; a large coloured bractea 

 which envelopes the principal 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; fo- 

 liated. 



SPA'TULATE. (from spathula, Lat.) 



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 nar- 

 row base, gradually widening by the la- 

 teral margins sloping out, and terminated 

 at the extremity by a sudden straight 

 line. 



SPE'CIES. (species, Lat.) 

 . 1. That which is predicated of many 

 things as the whole of their essence. 



2. In mineralogy, a species may be de- 

 fined, a collection of minerals, which are 

 composed of the same ingredients, and 

 combined in the same proportions. 



3. In entomology, a group of natural bo- 

 dies which agree together in all their 

 essential, unchangeable characters. The 

 idea of species comprises in it a congru- 

 ency, that is to say, not a mere conform- 

 ity, but also a resemblance of its indivi- 

 duals. Species is the lowest of all the 

 systematic groups, and, consequently, the 

 most fixed and conformable. 



4. In botany, according to Jussieu and 

 others, a species is a combination of indi- 

 viduals alike in all their parts. De Can- 

 dolle makes it " a collection of all the in- 

 dividuals which resemble each other more 

 than they resemble any thing else ; which 

 can by mutual fecundation produce other 

 individuals ; and which reproduce them- 

 selves, by generation, in such a manner 

 that we may from analogy suppose them 



all sprung originally from one single indi- 

 vidual." 



The physiological definition of a species 

 is, that all the individuals that belong to 

 it will breed together and produce suc- 

 cessors, having the same power of repro- 

 duction by seed. 



SPHA'GNOUS. Mossy ; containing peat- 

 moss. 



SPHA'GNUM PALU'STRE. A kind of moss, 

 generally constituting a large portion of 

 the entire mass of peat-bogs. The 

 sphagnum palustre has the property of 

 throwing up new shoots in its upper part, 

 while its lower part decays, and from this 

 circumstance it mainly contributes to the 

 formation of beds of peat. , 



SPHERE, (sphcera, Lat. crpatpa, Gr. sphere, 

 Fr. sfera, It.) A solid, generated by the 

 revolution of a semicircle about its dia- 

 meter, which remains fixed ; a globe ; an 

 orbicular body ; a body of which the 

 centre is at the same distance from every 

 point of the circumference ; such a solid 

 body that all lines drawn from its centre 

 to its surface are equal. The lines are 

 called radii. 



SPHE'RICAL. (spherique, Fr. sferico, It.) 

 Round ; orbicular ; globular. 



SPHERI'CITY. Roundness ; globosity. 



SPHE'ROID. (from atyaipa, a sphere, and 

 eldog, likeness, Gr. sferoide, It. spheroide, 

 Fr. corps solide, dont la figure approche 

 de celle de la sphere.) A solid body ap- 

 proaching to the form of a sphere. A 

 spheroid may be either oblate or prolate ; 

 an oblate spheroid resembles an orange, 

 having its poles flattened, such is the 

 form of the earth and planets ; a prolate 

 spheroid has its poles drawn out, and its 

 form somewhat resembles an egg. 



SPHEROI'DAL. Having the form of a sphe- 

 roid, whether oblate or prolate. 



SPHENO'-PTERIS. A very beautiful and 

 delicate genus of fossil ferns described by 

 M. Ad. Brongniart. Three species are 

 figured in Dr. Mantell's Geology of the 

 South- East of England, namely, Sphe- 

 nopteris Sillimani, named after Prof. 

 Silliman ; Sphenopteris Phillipsii, named 

 after Prof. Phillips ; and Sphenopteris 

 Mantelli, named, by M. Adolphe Brong- 

 niart, in honour of Dr. Mantell. 



SPHE'RULE. (spharula, Lat.) A little 

 globe ; a globule. 



SPHI'NCTER. (from tr^tyyo), Gr. to con- 

 tract ; sphincter, Fr.) The name given 

 to certain muscles whose office it is to 

 contract the part in all directions, draw- 

 ing it together as the mouth of a purse is 

 contracted by a circular string. 



SPI'CATE. (from spicatus, Lat.) Having 

 a spike or ear. 



SPI'DER. The different species of spiders 

 compose the genus named Aranea by 



