354 J. E. Duerden — Jamaican Actiniaria : Part I. — Zoanthece. 



tentacles as about 30, and the later one (1860, p. 331) states the disc and tentacles 

 to be violet. 



The Jamaican form also appears to be a larger, more robust species. External 

 characters readily separate it from G. brevis. G. isolata, described by M c Murrich, 

 from the Bahamas (1889), is also evidently quite distinct. It can likewise be 

 distinguished from the other known members of the genus — G. Macmurrichi, 

 Hadd. and Shackl. ; G. Mutuki, Hadd. and Shackl. ; and G. canariensis, Hadd. 

 and Duerd. — obtained from localities more distant. 



Gemmaria fusca, n. sp. 

 (PI. XVII. a, fig. 6.) 



Form. — Polyps erect, firm, cylindrical, growing in colonies from a thin lamellar 

 ccenenchyme or solitary; smooth above, with sand grains showing through the 

 ectoderm, and scarcely any adhering particles, but many more below. Capitulum 

 with about 30 ridges and furrows, may be slightly more or less ; greatly ex- 

 panded and overhanging in full extension. Tentacles dicyclic, smooth, acuminate, 

 overhanging in extension, short, slightly entacniseous. Outer part of disc over- 

 hanging in full extension, giving an umbrella-like appearance, with the radiating 

 mesenterial lines showing through ; central portion of disc appears as a rounded 

 elevation with the slit-like mouth at the apex, and is devoid of incrustations. 

 Ccenenchyme spreading and closely incrusting the upper surface of rocks and 

 stones, not very freely developed ; exposed surface rough, due to adhering cal- 

 careous particles. 



The individual polyps in a colony are usually closely apposed at the base, but 

 may be separated a short distance from one another, or may ultimately become 

 isolated. The polyps are practically the same diameter throughout, but may 

 diminish a little below, expanding again towards the base. In retraction the 

 distal part may be slightly swollen and rounded, with a central aperture; the 

 number of capitular ridges, which extend for some distance down the column, is 

 very variable. In preserved specimens the proximal part of the column is slightly 

 wrinkled, but the distal is smooth. 



Colour. — Distal part of column, tentacles, and disc dark brown ; proximal part 

 of column sand-coloured, often with foreign green matter ; oesophagus white. 



Dimensions. — Height of column varies from 1 to 3 cm., most are about 2*2 cm. ; 

 diameter 1 cm. ; inner tentacles 0*15 cm. in length. 



Localiiy. — Colonies and isolated individuals are found growing in considerable 

 abundance attached to coral rock and stones in the very shallow water around 



