236 THE MICROSCOPE. 



Indian Ocean, to the south-west of Malabar, there is a chain of reefs 

 and islets 480 geographical miles in length ; on the east coast of New 

 Holland, an unbroken reef of 350 miles long ; between that and New 

 Guinea, a coral formation which extends upwards of 700 miles ; and 

 that Disappointment Islands and Duff's Group are connected by 600 

 miles of coral reefs, over which the natives can travel from one island 

 to another." 



Nothing can be more impressive than the manner in which these 

 diminutive creatures carry out their stupendous undertakings, which 

 we denominate instinct, intelligence, or design. Commencing betimes 

 from a depth of a thousand or fifteen hundred feet, they work upwards 

 in a perpendicular direction ; and on arriving at the surface form a 

 crescent, presenting the back of the arch in that direction from which 

 the storms and winds generally proceed; by which means the wall 

 protects the busy millions at work beneath and within. These 

 breakwaters will resist more powerful seas than if formed of granite ; 

 rising as they do in a mighty expanse of water, exposed to the utmost 

 powers of the heavy and tumultuous billows that eternally lash against 

 them. It is almost unnecessary to remark, that the formations here re- 

 ferred to are not those of corallines alone, but of zoophytes also. 



BRYOZOA. 



Bryozoa were placed by Dr. Johnston under the head Ascidioida ; 

 in the generality of works they are named Bryozoa, and the individual, 

 Bryozoon ; derived from the Greek words fipvov, sea-moss ; wov, ani- 

 mal. (Plate I. Nos. 1, 2.) The distinction to be drawn between it 

 and those already described, consists in the polypidom being a living 

 portion of the polyp, while all others are unorganised ; and that most 

 of the zoophytes we have examined are devoid of cilia, whilst in the 

 Bryozoon these are most bountifully supplied. The play of the cilia 



DESCRIPTION OF PLATE I. (FRONTISPIECE.) 



1. Bryozoa Bowerbankia, or Bowerbank Bryozoon, showing its internal structure : 

 near it is a smaller animal completely withdrawn into its cell. 2. Eschara cervicornis, 

 or Sea-moss polyp : the animal is seen drawn out from its shell or chalky covering 1 . 

 3. Plumulaiia pinnata, or Feather polyp. 4. Campanularia volubilis, or Twining 

 polyp. These polyps are all represented slightly magnified. 5. Actinia rubra, or 

 Sea-marigold, near which is one shown retracted into its cell. 6. Actinia Bellis, or 

 Daisy sea-anemone ; a side view of the animal. 7. The same animal seen with its 

 crown of tentacles fully expanded. 8. Doris tuberculata. 9. Laniogerus Elfortii. 

 10. Aplysia ; all species of water-snails, the last without a shell-covering. Fronds of 

 Algse are represented growing amongst the rocks. In the title-page many other 

 specimens of marine Polyps, Actiniae, &c v are given. 



