140 J- K- DuERDEN — Jamaican Aetiniaria : 



Four to six very distinct, sucker-like verrucse are developed in each row, and 

 a few smaller examples may be continued below; the larger are capable of attach- 

 ing pieces of fine gravel, fragments of shells, etc., to the column. The rows of 

 verruc£B correspond with only certain of the mesenterial divisions as seen exter- 

 nally, and sometimes a single apical verruca ma)^ alternate with the principal rows. 



A circle of prominent, rounded acrorhagi occurs at the apex of the column ; 

 these are double in number the rows of verrucfe, and alternate with the outermost 

 row of tentacles. Sometimes a smaller acrorhagus alternates with the larger. A 

 shallow fossa intervenes between the cycle of acrorhagi and the commencement of 

 the tentacular region. 



The peripheral tentacles are numerous, slightly entacmseous, shortly conical, 

 and overhanging, the oral face being longer than the external. The number 

 varies; the normal arrangement ajipears to be 6, 6, 12, 24, 48, &c. ; one specimen 

 bore 19, instead of 15, enclosed within the radii from two tentacles of the first 

 cycle ; the tentacles of many small polyps were counted in which the normal 96 

 were present, while in one specimen the irregular number 106 occured(Pl. x., fig. 1), 



In the majority of polyps, the tentacles bear several transverse, opaque 

 thickenings, most strongly developed along the oro-lateral area of the tentacles, 

 where a distinct bilobation is often observable (PI. x., fig. 2). Six or seven pairs of 

 tubercles, arranged pinnately, may be present on the larger tentacles, diminish- 

 ino- a little in prominence both proximally and distally. The tentacles are smooth 

 for some little distance from their origin, and remain so throughout their outer 

 concave aspect. 



Many polyps were procured wholly destitute of the thickenings, the tentacles 

 being quite smooth, differently coloured, and presenting an entirely distinct 

 appearance from the usual form. At first I had no hesitation in regarding these 

 as a second species ; but an acquaintance with scores of specimens, all living 

 within the same area, revealed every stage in the presence or absence of the 

 tubercles, some examples having only odd tentacles smooth, while others have 

 only a few tuberculated. 



The disc is very large, thin-walled, and, periphally, is thrown into 8-12 folds, 

 and may overhang the column to a great extent ; its middle region is flat, or may 

 be slightly convex. The surface of the disc is characterized by the presence of 

 small, wart-like projections, varying in size and arranged mostly radially; thej'- 

 correspond with the first and second cycles of tentacles, and sometimes with the 

 lower orders. In large specimens, the tubercules may extend in great numbers 

 over nearly the whole of the disc, even as far as the peristome, and vary consider- 

 ably in number, size, and distance apart in each row. Before the peristome 

 is reached they become more closely and irregularly arranged, and seem to 

 correspond with all the mesenterial spaces (PI. x., fig. 1). 



