In Millepora the Iarge nematocysts are oval or almost spherical in shape, and the 

 long thread has a broad belt of thorns in the middle. In all the Stylasterina in which the 

 large nematocysts have been found, their shape is much narrower and might be described as 

 spindle-shaped ; and, according to Moseley, the belt of thorns is at the base and not in the 

 middle of the thread. As regards the smaller kind of nematocysts, the three-spined type so 

 characteristic of Millepora has not been found in any Stylasterid. 



The solid scalariform endoderm of the dactylozooids is another very distinctive feature 

 of the family. In all the specimens of the genus Millepora that have been examined the 

 dactylozooids show a cavity extending from the apex to the base and the endoderm cells are 

 very similar to the endoderm cells lining the coenosarcal canals. The scalariform tissue is 

 clearly a much more differentiated tissue than this and taken with other characters suggests 

 that the Stylasterina are a more specialised group. 



The general characters of the gonophores of Stylasterina form another important point 

 of difference from Millepora. The discovery of ampullae in a variety of Millepora called M. 

 murrayi by Ouelch ') suggested that the gonophores might be similar to those of Stylaster; 

 but the discovery by one of us 2 ) that the ampullae bear medusae proved the error of this 

 supposition. Whether the gonophores are or are not adelocodonic gonophores, as suggested 

 by Moseley, may be a matter open still to discussion but if they are they show features ver}' 

 different from those of any other adelocodonic gonophores in the Hydrozoa. The specialisation 

 of the trophodisc in the female gonophore, whether we regard it as a modified manubrium 

 or not, to purvey nourishment to the growing eggs is a definite and distinct character of 

 the Stylasterina. 



Family Stylasteridae 

 with the characters of the order. 



Of the 14 genera of recent Stylasterids, Stylaster, Errina, Cryplolielia, Conopora and 

 Distichopora are represented in the collection. The genera Allopora, Astylus, Sporadopora, 

 P/ialangopora, Pliobothrus, Laöiopora and Spinipora are not represented in the collection. We 

 consider that the genus Stenohelia is not distinct and should be merged with Stylaster and 

 that the genus Lepidopora (Pourtales) as pointed out by Moseley, is not distinct and should 

 be mero-ed with Errina. The genus Phalangopora (Kirkpatrick) 3 ) differs from Errina in the 

 absence of a style in the gastropore but in other respects comes very close to it. A new 

 o-enus Stemnopora is constituted for a fragment of a coral of verv remarkable structure. 



Of the five genera represented in the collection Stylaster and Distichopora occur in 

 shallow water. Stylaster extends from quite shallow water on the reefs into deep or very deep 



1) J. J. Quelch, Challenger Reports, Vol. XVI. 



2) 1. c. p. 1. 



3) R. Kirkpatrick, Ann. de Mag. Nat. Hist. March 1887. 



