Boone, Coelenterata, Cruises of "Ara" and "Alva" 71 



Body-wall : The ectoderm is so thoroughly penetrated by the 

 encrustations of sand, shell, etc., that it is difficult to determine 

 the character of the ectodermal cells. The mesoglea adheres in 

 coarse strands and forms a distinctive layer beneath the cuticle. 

 The lacunae are large, irregularly oval to subcircular, their inter- 

 stitial border being mesogleal threads. The body- wall appears to 

 be pierced by longitudinal canals, from base to disk, some of which 

 anastomose by finer canals. The endoderm lining the column 

 forms a regular layer of large cells. The muscle tissue is well 

 developed. The sphincter is single, well developed, mesogleal. 



Disk and tentacles : The ectodermal layer is well developed, 

 but it and the mesoglea are much penetrated by the partially em- 

 bedded encrustations. No zoanthellae are present but cell enclos- 

 ures, similar to those described and figured by McMurrich% also 

 Haddon and Shackleton% appear to be present in this new species. 



Aesophagus : The groove is well marked, truncated. 



Mesenteries: These are typical Brachycneminae, arranged 

 as shown in text figure 4. The mesoglea is very well developed in 

 both series, the muscular layer also being well developed and the 

 mesogleal plaitings well defined. Each mesentery has a con- 

 spicuous vertical canal running through it from the base of the 

 polyp to the disk. In the aesophagal region this canal apparently 

 does not divide, but does become of wider diameter. The endoderm 

 is similar to that of the body-wall. The ectoderm seems to form 

 a regular layer. The mesenterial filaments are large, their meso- 

 glea thin and endoderm similar to that of the mesenteries. 



Gonads: Numerous mature ova are present in one of the 

 specimens cut. 



Remarks: The present species is necessarily established, 

 since it differs anatomically from the earlier described Australian 

 species of Gemmaria, namely, Gemmaria macmurrichi Haddon 

 and Shackleton*^ and G. mutuki Haddon and Shackleton,® both of 

 which are from Torres Straits ; G. arenacea Wilsmore' from Mast- 

 head Island, Queensland, and from G. Willeyi Whitelegge,^ de- 

 scribed from Funafuti, Ellice Islands. 



'Gemmaria rusei McMurrich, J. P., Proc. Acad. Nat. Sci. Phila., 1889, p. 124, pi. 7. fig. 7-9. 



^Gemmaria macmurrichi Haddon, A. C, and Shackleton, A. M., Trans. Roy. Dublin Soc., 1891, 

 ser. 2, vol. IV, p. 688, pi. 61, fig. 1, pi. 63, fig. 7; Ibid, G. Mutuki, p. 689, pi. 61, fig. 10. 



''Gemmaria arenacea Wilsmore, L. G., Journ. Linn. Soc. Zool., 1909, vol. XXI, p. 323, pis. 43, 

 45, figs. 16-20. 



^Gemmaria willeyi Whitelegge, T., Mem. Austral. Mus. Sydney, 1896-1900, vol. Ill, pt. 7, 

 1899, p. 387, pi. 24, figs. 1 and 4. 



