343 



According to Rnedemann's* ol)servatioiisthe voiiiig Di])lo- 

 graptiis upon leaving- the gonophore has ah'eadj advanced 

 into the sicuhi stage, so that a free-swimming phumhi stage 

 appears not to exist. It is probal>le that this is trueot" most, 

 if not all, graptolites, and that hence the distribution of 

 these animals is such as will be accounted for by the vicissi- 

 tudes which they met with while a floating colony. 



Anthozoa. — The Anthozoa are typicalh^ marine sedentary 

 benthonic animals, inhabiting chiefly the warmer waters of 

 the oceans. A large number are without hard supporting- 

 parts, and, consequently, leave no remains ; while others, 

 probably the majority of Anthozoa, secrete a calcareous or 

 hoi-ny corallum, whicli is capable of preservation. Among 

 the Actinaria, or fleshy polyps, a certain amount of locomo- 

 tion of a creeping ov gliding nature is often observable 

 (Metridium, etc.), the individuals possessing this ability 

 thus passing from a normal sedentary to a vagrant ben- 

 thonic life. A few forms are also met with among the plank- 

 ton. Occasionally, pseudo-])lanktonic individuals are met 

 with attached to floating- algiB or timbers, and })seudo- 

 vagrant benthonic individuals attached to moving crusta- 

 ceans are not unknown. 



The Maclreporarias or stone corals, are normally seden- 

 tary forms, though they are not necessarily attached, but 

 may rest upon the sands. (Fungia, some Porites.) Though 

 the normal medium of the Anthozoa is salt water, a few are 

 known in brackish and even in tolerably fresh water. Cilicia 

 rubeola is reported by the " Challenger"' f in the river Thames 

 in New Zealand; and Dana? states that"* * " upon the 

 reefs enclosing the harbor of Rewa (Viti Lebu), where a 

 large river, three hundred yards wide, empties, whicli during 

 freshets enables vessels at anchor two and a half miles off 

 its mouth to dip up fresh water alongside, there is a single 

 porous s[)ecies of Madrepora {M. cribripora), growing here 



*Rueclemann, R., Development and Mode of Growth of Diplograptns. MeCov. Uth 

 Ann. Rep. N. Y. State GeoL, 1895, pp. 219-249, Pis. I.-V. 

 tReport, Vol. XVI., II., p. .36. 

 t Corals and Coral Islands, 1872, p. 120. 



