254 THE OCEAN WORLD. 



single orifice in the centre of the lower surface of the body, destitute 

 of teeth, performing the functions both of mouth and anus. De 

 Blainville says that "the liver is well marked and rather considerable 

 in the star-fishes, forming bunches occupying the whole circumference 

 of the stomach, and extending to the cavities of the appendages where 

 these exist." The mouth and gullet is admirably adapted for securing 

 the testaceous molluscs and other substances on which they feed. 



Reproduction in the Echinodermata appears to be monoecious. 

 Ovaries are, as far as is known, present in all the female forms. They 

 vary in number in different species. The sexes are usually separate : 

 the young are produced by eggs, the embryo of which undergo im- 

 portant metamorphoses. Immediately after birth, the young star-fishes 

 have a depressed and rounded body, with four club-shaped appendages 

 or arms at their anterior extremity. When they are a little more 

 developed, papillae may be observed on the upper surface, in fine 

 radiating rows : after twelve days the fine rays begin to increase, and 

 after eight days more two rows of feet, or ambulacra, are developed 

 under each ray, which assist in the locomotion of the animal by 

 alternate elongation and contraction, performing also the office of 

 suckers. Like most other of the lower animals, they have the power 

 of reproducing parts of their bodies which may have been accidentally 

 destroyed. 



Most starfishes have five perfectly equal arms. They resemble a 

 cross of honour, which has five branches. The star of the brave, the 

 star of honour these somewhat trivial words recall, nevertheless, the 

 resemblance which exists between the two objects; doubtless, man 

 has here taken Nature for his copy. It must, however, be remarked 

 that, though five is the general number of arms in the star-fish, this 

 number is not constant ; it varies with different genera, species, and 

 even with individuals. The connection of the arms with the disc 

 presents equally remarkable differences. In the genus Culcita, the 

 disc is so much developed that it constitutes, so to speak, the entire 

 animal, whilst the arms form only very slight protuberances upon its 

 circumference. In the genus Luidia, on the contrary, the disc is 

 reduced to a minimum, whilst the arms are of great length, and very 

 slender. 



The colours of the many species of star-fish vary greatly ; they 

 vary from a yellowish-grey, a yellow-orange, a garnet-red, to a dark 

 violet. 



Star-fishes are exclusively and essentially inhabitants of the sea ; 

 they are never met with in fresh water ; many of them dwell amongst 

 the submarine plants, others are found on sandy coasts ; they generally 



