Biblioyraphical Notices. 1 29 



Older II. Spinighada. Ophiurid.^: — Disappearance of brachial mem- 

 branes, cirrlii as before ; true arms clothed with spines for 

 motion. 



III. CiRRHiGRADA. AsTERiAD.E — Arms disappear; body more or 



less lobed, and lobes channeled beneath for cirrhi, which act 

 as suckers, and are the organs of motion. 



IV. Cirrhi-Spinigrada. Echimd^ — Gradual disappearance of 



lobes ; cirrhiferous canals appearing as avenues where cirrhi 

 act as in Order III., but are assisted by mobile spines clothing 

 the integument. 

 V. Cirrhi-Vermigrada. HoLOTHURiADiE — Lobcs disappear ; mo- 

 tions affected by avenues of cirrhi, assisted by contraction and 

 extension of the soft body. 

 VI. Vermigrada. SipuNcuLiDiE — Clrrlu become obsolete and dis- 

 appear ; motion effected by the contraction and extension of 

 the animal's body. 



" All the Radiata," it is remarked, " are greatly influenced in the 

 arrangement of their parts by some definite number. In the Echi- 

 nodermata the reigning number is five. The name of ' five-fingers,' 

 commonly applied by mariners to the Starfishes, is founded on a po- 

 pular recognition of the number regnant." 



'• Every plate of the Sea-Urchin is built up of pentagonal particles. The 

 skeletons of the digestive, the aquiferous, and the tegumentary systems, 

 equally present the quinary arrangement ; and even the cartilaginous frame- 

 work of the disk of every sucker is regulated by this mystic number. When 

 the parts of Echinoderms deviate from it, it is always either in consequence 

 of the abortion of certain organs, or it is a variation bi/ representation, that 

 is to say, by the assumption of the regnant number of another class. Thus 

 do monstrous Starfishes and Urchins often appear quadrate, and have their 

 parts fourfold, assuming the reigning number of the Actinodermata, con- 

 sistent with a law in which I put firm trust, that when parallel groups vary 

 numerically by representation they vary by interchange of their respective 

 numbers." 



We pass by the excellent tables showing the distribution of spe- 

 cies, both in regard to the zones of the sea and the coasts of the Bri- 

 tish Isles, and proceed to the consideration of the several orders into 

 which the Echinodermata are divided. The first is the Crimidece, of 

 which we have now but one living British species The former 

 abundance and present scarcity of these singular and interesting 

 tribes is thus announced in the opening paragraph, in which the 

 beauty of the diction is surpassed only by the elevation, the gran- 

 deur and poetic interest of the ideas which it embodies. 



"One of the most remarkable phfenomena displayed tons by the researches 

 of the geologist, is the evidence of the existence, in primaeval times, of ani- 

 mals and plants, the analogies of which are now rare or wanting on our 

 lands and in our seas. Among those tribes which have become all but ex- 

 tinct, but which once presented numerous generic modifications of form and 

 structure, the order of Crinoid Starfishes is most prominent. Now scarcely 

 a dozen kinds of these beatiful animals live in the seas of our globe, and in- 

 dividuals of these kinds are comparatively rarely to be met with : formerly 

 they were among the most numerous of the ocean's inhabitants, — so nume- 

 rous that the remains of their skeletons constitute gi-eat tracts of the dry 

 land as it now appears. For miles and miles we may walk over the stony 



Ann. S^ Mag. N. Hist. Vol. xi. K 



