TUBULIPORID.E I DIASTOPORA. 277 



1. D. OBELIA, crust tkin, closely adnate ; cells with an even 

 entire aperture. Dr. Fleming. 



PLATE XLVII. FIG. 7, 8. 



Millepora reticulum? Esper Millep. tab. 11, fig. 1, 2. Berenicea hyalina, Flem, 

 Br. Anira. 533. Obelia tubifera, Gray Zool. Misc. 35. Tubulipora obelia, Johns. 

 Brit. Zooph. 269, pi. 30, fig. 7, 8. Couch Zoopb. Cornw. 47 : Corn. Faun. iii. 

 108. Tliompson in Ann. Nat. Hist. v. 252. 



Hob. In deep water at Scarborough, on Modiola vulgaris, rare, 

 W. Bean. I find it on the same shell in Berwick bay, G. J. Com- 

 mon on shells and stones on the coast of Cornwall, R. Q. Couch. 

 Not uncommon in Devon, C. W. Peach. Shores of Ireland, W. 

 Thompson. I have seen several specimens on Lima fragilis dredged 

 off Sana Island by Mr. Hyndman and in the collection of Mr. 

 Thompson ; and have had it also from the Rev. D. Landsborough. 

 It has a preference to the Pinnae. 



Crust rather thin, entirely and very closely adherent, chalk-white, 

 even, spreading in somewhat circular expansions : the cells alternate, 

 rather distant, rowed, radiating from several centres, divided by paler 

 lines, horizontal, tubulous, mostly immersed, the mouths raised with 

 a round oblique plain aperture. 



" The tubes or cells," Mr. Couch has correctly remarked, " vary 

 very much in their appearances, being either erect, semi-erect, pro. 

 minent, or immersed, and in some specimens all these varieties occur 

 together." In general, however, they are much more immersed in 

 the crust than is usual in the Tubuliporidae, and instead of their 

 elevated apertures opening on a line so as to form a transverse series, 

 they are pretty constantly alternate. The basal lamina extends a 

 narrow thin border beyond the cells, and is so cemented to the shell 

 on which it grows that it cannot be detached without destruction. 



This polypidom has great resemblance to the D. verrucosa and 

 gracilis of Milne-Edwards, especially to the latter (See Ann. des Sc. 

 Nat. n. s. ix, pi. 14, fig. 2 and 3.), from which, indeed, I know not 

 how to distinguish it. The D. gracilis is a fossil ; and, besides it, 

 we have five other native fossil species. 



3. IDMONEA,* Lamouroux. 

 CHARACTER. Polypidom calcareous, divided dichotomously, 



* Idmonea, probably from Idmon, one of the Argonauts, who acted as prophet to 

 the expedition. Ifpaiv, knowing, sagacious. 



