19 



scribed by Haddon (1801) in Parazoanthas. [u transverse sections 

 tlirough the columii wall these lacunae are very distinct, forming a 

 series of elongated ovai spaces, separateti from one another by di- 

 stinct interwals, but extending comple- 

 tely around the column. 



The mesenteries in one half of the co- 

 lumn circumference, ali I could count 

 with certainty in my preparations, were 

 iwenty-three in number, and it may be 

 assumed that the total number was so- 

 mewhere in the neighborhood of fift'y. 

 They were very thin, the basai canal in 

 sections below the level of the stomato- 

 daeum appearing as elongated slits. 



There is nothing in Lesueur's descri- 

 ption of this species to distinguish it de- 

 finitely from socìatus, and the correctness 

 of Duchassaing and Michelotti's identifi- 

 cation must remain uncertain, but ne- 

 vertheless may well be accepted. Iden- 

 tifications of the species have also been 

 made by Mùller (1884), Duerden (1898) 

 and Verrill (1000). The absence of any 

 structural data with regard to Verrill's 

 specimens, which carne from the Bermu- 

 das, makes it impossible to discuss the 

 correctness of their identification. Mùller found thirty-eight mesente- 

 ries in one of his polyps, which measured 2.5 cm. in height and had 

 a diameter of 0.7-0.0 cm., and he notes that the column mesogloea was 

 of considerable thickness, reaching in parts 1 mm. He makes no men- 

 tion of any spaces in the column mesogloea, which could hardly fail 

 to attract attention if developed to the sanie extent as in Duchas- 

 saing and Michelotti's form, and he described the mesogloea of the me- 

 senteries as being strong and traversed by lacunae of varying size. 

 Altogether his form seems to present little similarity to Duchassaing 

 and Michelotti's and resembles much more closely their Z. flos-ma- 

 rinus. 



Duerden gives Z. diibhis as a synonym l'or Z. solanderi, but in 

 this I think he is mistaken, since, as I have shown above, solanderi 

 presents very different structural characters, notably in the form ol 

 the sphincters, in the occurrence of the sub-ectodermal cavities, in the 

 form of the coenenchyme, and, it may be added, in the thickness of 

 the column mesogloea, which does not show the transiucency of that 



Fig. 6 



