No. 435-] 



NOTES AND LITERATURE. 



Cotylea — Pericelida? — is erected. The most abundant family is 

 that of the Pseudoceridae. Two spec ies found in the Maldives occut 

 also in the tropical Pacific and two species, Lcptoplana trcmcllar.s 

 and Thysanozoon brocchii, are widespread, occurring in north tern 



Finally Gardiner himself has a paper on "Special observations and 

 work relating to the formation and growth of coral reefs," still incom- 

 plete. He brings additional evidence, based on an increase in depth 

 and extent in the lagoons since 1836, for believing that they are due 

 to solution. The results of dredging at depths from 16 fathoms to 

 50 fathoms, show that the reef corals do not flourish luxuriantly 

 below 25 fathoms, but there are other genera of corals which "flour- 

 ish just beyond where the surface forms cease to exist." To test the 

 rate of growth of reefs Gardiner studied the size of corals gathered 

 from a channel that had been cleaned out three years before. He 

 concludes that the reef grows at about the rate of 16 fathoms in 

 1000 years. He suggests that " if Falcon Island, erupted to a height 

 of about 250 feet in 1885 and now a mere shoal, be cut down to 25 

 fathoms by the end of this century its place might well be marked 

 by surface reefs, perhaps even by a perfect atoll, considerably before 

 the year 3000 A. D." Finally the action of boring and sand-feeding 

 organisms is discussed. The boring forms include alga; of the 

 genus Achyla, Cliona and a Myxospongid, the mytilid Lithodomus, 

 bipunculoidea, a cirripede Lithrotrya and, especially, the Polycha-ta, 

 above all the Eunicidae. Of the sand feeding organisms the Holo- 

 thuroidea, the Echinoids, the enteropneust Ptychodera, Sipunculus 

 and Thalassema are important. All these organisms help in the 

 dissolution of the coral rock by which the lagoons are made and 

 kept open. C. B. D. 



A Book on the " Birds of the Rockies" 1 might be either a care- 

 ful scientific hand-book of that region, or an introduction to popular 

 bird study, or a pleasant account of ornithological rambles. The 

 first Mr. Keyser's book does not of course claim to be: if it is to be 

 judged, as the second or third, we must look for enthusiasm, for a 



is a wide field open to writers who have been trained in the school 

 of Burroughs and Torrey, who can write introductions or invitations 



