116 THE BERMUDA ISLANDS. 



below the margin, but internal to it. In all the Bermuda speci- 

 mens, of which there are quite a large number, a well-marked 

 margin is present and Hertwig describes in his form a fold of the 

 column-wall which must be considered equivalent to the mar- 

 gin of tlie other species. Although the margin cannot be con- 

 sidered of importance as marking the boundary of the disc, 

 yet it is a structure of frequent occurrence and must be taken 

 account of. Structures that occur on the column-wall below 

 it, as in Hormathia, cannot be considered identical for syste- 

 matic purposes with others which invariably lie above or 

 internal to it, and are not quite similar in form. 



It must be noticed that Haddon has recently referred to 

 Gosse's Hormathia a form* altogether different from that as- 

 signed to it by Hertwig. The correctness of Haddon's iden- 

 tification is quite as doubtful as Hertwig's, if not a little more 

 so. The form is certainly a Sagartid, and probably a Phellia, 

 it being stated that it is very similar to Hertwig's Phellia 

 pedinata. 



Hertwig refers his Diplactis (Hormathia) delicatula to the fam- 

 ily Antheadse, on account of the diffuse endodermal nature of 

 sphincter. The situation of the mus-^le and other characters 

 make it evident that Diplactis should be associated in the same 

 family with Ouladis. In the Phyllactidse as here limited we 

 have several grades of complication of the fronds. In Dipladis 

 their structure is exceedingly simple, being simply digitiform 

 in D. Bermudensis and club-shaped in D. delicatida. In O.fasci- 

 culata they are somewhat more complicated, and from this the 

 passage is easy to Verrill's 0. [Lophadis) omata, and from this 

 to the very complicated structure seen in 0. flosculifera. 



Diplactis Bermudensis. n. sp. (PI. 10, figs. 4 and 6, PI. 11, figs. 1 and 2.) 



A number of specimens of. the form for which I propose this 

 name were obtained. The majority were in a partially con- 

 tracted condition, but apparently the power of contraction is 

 not fully developed, as in none were the tentacles completely 



* A. C. Haddon — On two species of Aciiniae from the Mergui Arcliipel.njjo. — 

 Jouni. Linn. Soc. Vol. XXI. 1888. 



