THE ANIMAL LIFE OF THE GROUP. 475 



fauna would doubtless add many new forms to the list of Hawaiian species. 

 For example, a large flat white species apparently undescril)ed, perhaps a 

 coronet barnacle,^'' attaches itself to the skin of the sen tui'tle. IMoreover, there 

 are doubtless examples of the truly parasitic species that are still more degen- 

 erate in form and habit and occur as parasites feeding on the larger crus- 

 taceans. 



Common Corals. 



The fragments of coral occasionally cast up on the sand beach are suffi- 

 cient to awaken in everyone a desire to know more of the life and hat)its of 

 the living creatures that produce the curious stony structure, and this desire 

 has tempted many to explore for themselves the wonderful reefs for which the 

 islands are so celebrated. 



The public long ago accepted, apparently without (luestion. the assertion 

 of a worthy poet ^o that the coral animal was an insect, Zoiilogists, however, 

 have long known that it is not an insect, but a polyp — a very different creature, 

 indeed — belonging to the great phylum,-i including all such animals as 

 hydroids, corals, sea-fans, sea-pens, jellyfish, sea-anemonies and their allies. 



There are, of course, many kinds of polyps, varying through a great 

 variety of shapes and sizes, but they all conform fairly w^ell to a genci-al plan 

 of body structure, a little more complex in its organization than that of the 

 sponge. They have a more or less typical cylindrical body, with an interior 

 cavit.y connected with the outside world by a single large opening at the free 

 end. This opening is surrounded by a circle of arm -like processes or tenta- 

 cles, hence the name polyp, meaning "many-footed." The tentacles aiv con- 

 tinuations of the body wall and composed of the same tissues. The fresh- 

 water Hydra, a minute animal less than an eighth of an inch in length,'-- is 

 usually figured as the type of the whole great phylum. But for our purpose 

 the common type of sea-anemonie, of which there are many sj^ecies living on 

 the rocks and along sandy shores or attached to piles and whai-vcs. may he 

 taken as an enlarged example of a single polyjx The chief difference betAveen 

 the two is that the animals known as the coral polyp usually lixc in ciioniious 

 colonies and form skeletons of lime,-'' whereas the sea-anemonies are solitary, 

 or at most gregarious, and secrete no hard skeleton. Both tlie anemonies-'* 

 and the calcareous corals,-'' however, are included in the same class.-" Though 

 belonging to different orders, thev seem to have the saine ueneral food liabits. 



1^ Coronula sp. -° Alexander Montgomery. "' Cnelenterata. 



^~ This interesting animal has not so far been reported from the fresh water pools and streams of Hawaii. 



-'Calcium carbonate. ^■^ Actiniaria. "^ Madreporaria. -" Anthozoa or Artinnzoa. 



(Description of Plate Continued from Opposite Page.) 



7. Podophthalmus vigil (male). 8. Calappn hrpatiea (male). 9. Carpilins convex^is. 10. 

 Calcinv^ elegayis. 11. Ocypode ceratoplithuhtia. 12. Cahippa hepatica (female). 13. Grap- 

 SKS grapsus ienuicrusiaiuft. 14. Cairiiuis hitens. 1.1. (\irpilius macii.hitiis. ](>. Chdonohia 

 testudinaria. 17. Elisus Ja'viiiianus. 18. Metopograpsus mcssor. 19. Cnhippa hepatica. 

 20. Metopograpsus messor. 21. Balanus amphitrite. 22. Macrophthalnuis lelescopicus. 23. 

 Tltalnmifa integra. 24. Forfunu.^ sanguinolentua. 



