Coelenterata. 



perforate hard tissues. Siderastrea radians, the skeleton of which is slightly 

 perforate, and is made more spongy by the presence of synapticula, withstands 

 exposure better. Forties seemed to be not at all affected by an exposure of 

 several hours, the extremely porous skeleton insuring a continuous supply of 

 water through capillarity. Madreporarian colonies are limited in growth, i. e. 

 in the amount of asexual reproduction. Records are given showing the rate of 

 growth of Emm., Dichoccenia, Fama, Man., Sid., Agar., For., Oc. and Hcc- 

 andra. A young Oc., probably a year old, was 32 mm. in diameter in its 

 basal expansion, and 28,5 mm. in a vertical plane; one branch projected hori- 

 zontally 22 mm. from the basal expansion. The annual growth-rate of other 

 specimens was from 15 to 35 mm. in height. A specimen of Mceand. areol. 

 was 40 mm. long in 1908, 54 mm. in 1909, and 80 mm. in 1910; the corre- 

 sponding breadths being 27, 46, and 69 mm. Its height in 1909 was 28 mm., 

 and, in 1910, 42 mm: This specimen was (in 1910) about 4 years old, and 

 almost adult. Plannlse of For., Favia and Ag., allowed to attach themselves 

 to tiles, developed into young colonies with several calicles; the duration of 

 the free-swimming stage varied from 6 to 23 days. 



Gerth describes, from the Moluccas, Lovcenipora 1 and Alveopora 1 n. He 

 points out that Favosites is divisible into two groups. In the first group 

 (gothlandica as type) the colonies are flat or rounded, but unbranched, the 

 tubes are polygonal and approximately equal in size, and the septal structures 

 are thorns of which there are 12 large ones between the pores. In the second 

 group (forbesi as type) the colonies are knobby or branched, some tubes are 

 larger than the rest, and the septal structures are represented by tracts of 

 granules irregular in number. The first group only contains true Hexacorallia 

 and is the predecessor of Alveopora, the second has affinities with the living 

 Alcyonaria. Somphopora is a F. which has advanced a stage towards Alveopora. 



i 



B. Alcyonaria. 



See Gravier( 4 ) and Kiikenthal, For fossil forms see Foerste, Gerth, Her- 

 mann, Parona & Crema & Prever, Richarz, and Yabe. As to regeneration in 

 Leptogorgia s., supra p 11, Wilson. 



Cylkowski points out that in the Alcyonacea dimorphism is restricted to 

 the Xeniidse and Alcyoniidse, but is not constantly exhibited even by species 

 of the same genus (e. g. Sinularia) ; and some colonies of Xenia fuscescens have 

 dimorphic polyps while others have not. Dimorphism is seen in only a few 

 genera and species of Gorgonacea, but is general, and usually well-marked, in 

 Pennatulacea, in some of the higher species of which even trimorphism occurs. 

 There are a few cases both in Alcyonacea and Gorgonacea in which the gonads 

 are borne only by the siphonozooids. 



Hickson( 2 ) describes Ceratopora n. nicholsonii n., obtained off Cuba in 100 fms. 

 It consists of a mushroom-shaped mass capped by a thin brown lamina, nearly 

 circular in outline and about 42 mm. in diameter, composed of small short 

 vertical tubes, which perforate the corallum to a depth of about 1 mm. Each 

 tube narrows rapidly from above downwards and ends in a blunt, conical de- 

 pression. The tubes do not communicate with one another below the surface, 

 and there are no tabulae. The brown colour of the superficial part of the 

 tube fades away, as the walls are traced downwards, into a pure white. Long 

 and very slender tuberculate spicules, all arranged parallel with the long axis 

 of the tubes, are partly imbedded in the walls and partly project on the surface 

 or into the cavities of the tubes. The walls of the tubes, as they were formed 



