he found in the number of tentacles of the gastrozooid, giving 12 as the number in Allopora 

 and 8 in Sty laster \ bnt the number of tentacles on the gastrozooids is much too variable for 

 diagnostic purposes. In S. gracilis l ) 1 2 tentacles have been found and we have found in ,S'. 

 ülogranus 4,5, 6 or 7 tentacles. 



As regards the characters mentioned by Moseley in these words "a strong tendency 

 towards the development of the cyclosystems on the lateral margins of the branches only. 

 Cyclosystems arising from one another by alternate gemmation", we may say that the alternate 

 gemmation is onlv pronounced in those forms arranged in the groups A. and D. in which 

 the cyclosystems are confined to the lateral sides of the branches, or to one surface only of 

 the flabellum. In the other groups the alternate gemmation is not nearly so conspicuous, even 

 if, in some cases, it may be rightly said to occur at all. 



However for the present we think it is advisable to keep the species attributed to 

 Allopora distinct, fully recognising the close relationship they have with this large and very 

 variable erenus. 



& 



This is the most abundant and widely spread genus of the family. No less than 29 species 

 have been described. They may be arranged according to a suggestion of Studer 2 ) as follows: 



A. Cyclosystems on lateral sides of the branches only. 



5". flabclliformis Milne Edwards and Haime. 5. bellus Dana. 



■S. gracilis Milne Edwards and Haime. 5". tenuis Verrill. 



S. amphiheloides Saville Kent. 5. eximius Duchassaing and Michelotti. 



S. punctatus Pourtales. 5. laevis Studer. 



5. filogranus Pourtales. S. verrucosus Studer. 



■S. asper Saville Kent. 5. bilobatus sp. n. 



5. densicaulis Moseley. 5. multiplex sp. n. 



5". infundibidifera Lamarck. 



B. Cyclosystems on lateral sides of branches and a few on the surfaces. 



S. roseus Milne Edwards and Haime. S. erubescens Pourtales. 



5. sanguineus Milne Edwards and Haime. 5". elegans Verrill. 



5". gemmascens Milne Edwards and Haime. S. pulcher Dall. 



C. Cyclosystems evenly distributed over the surfaces of the branches. 



S. p-rauulosus Milne Edwards and Haime. 5. stellalatus Stewart. 



D. Cyclosystems on the anterior surface of the branches only. 



S. complanatus Pourtales. 5. tiliatus sp. n. 



S. obliquus Studer. 5. minimus sp. n. 



S. virginis Moseley. 5. iimbouatus sp. n. 



1) S. J. HlCKSON. Proc. Roy. Dublin Soc. VII, 5. 



2) Th. Studer. Monatsber. der K. Akad. Berlin 1877. 



