1863.] DUNCAN WEST INDIAN COKALS. 439 



wound is evidence of a former appendicular attachment. Calice very 

 long, gutter-shaped, on an even plane ; margin very narrow, slightly 

 elevated at the extremity, and compressed a little here and there. 

 Septa very numerous, sixty to one inch ; primary, secondary, and 

 tertiary nearly equal; very delicate, rounded above, finely granu- 

 lated, and barely exsert at the wall ; the small septa which extend 

 well inwards are numerous, and a large septum is succeeded by one 

 of these, then a middle-sized one follows. Inner margins very de- 

 licate, rounded, and separated from those opposite by the space which 

 leads down to the columella. Costse indistinct, parallel. Columella 

 essential, lamelliform, free, sharp, very long and continuous, joining 

 the septa (out of sight) by trabecule. Length (fractured specimen) 

 2 inches 4 lines ; breadth 6 lines ; height ^ in^h. 



A Coral of unique shape. It is very different from the other 

 species of the genus, but its columella and its deficiency of pali and 

 endotheca prove it to be a form of Placotrochus. 



3. Thysanps excenteictjs, gen. et spec. nov. PI. XVI. figs. 3 a-S c. 



Five specimens of a simple Coral (Nos. 1-5), in the British 

 Museum, very unusual in shape, and all specifically related, have 

 the following characters. The description is taken from No. 1, a 

 young individual. 



Corallum simple, resembling in shape a half-folded ovate leaf, the 

 lobes of whose base are joined, the petiolar junction being still evi- 

 dent. There are three angles to the corallum: — 1. An inferior and 

 anterior angle which projects forwards and obliquely downwards (the 

 petiole of a leaf would be attached here) . 2. A superior and anterior 

 angle, which is immediately above the first, and is connected to it 

 by a linear and concave furrow ; it is situated at the anterior rounded 

 overlapping margin of the calice, and this margin forms the base of 

 a triangle, of which the inferior angle is the apex. A lateral view 

 shows a curve between the calicular end and the pointed inferior angle. 

 3. A posterior angle is produced by a curved line passing backwards 

 and downwards from the first angle, which joins the posterior calicular 

 end, and forms a gutter-like extremity. The line from the first to 

 the third angle is the base in the ordinary sense ; this base is linear, 

 and is marked by a rounded shallow keel. There is an erosion or 

 spot in some specimens, where the corals were once attached, imme- 

 diately above the first angle. There is a general curve of the re- 

 ceding lines to the left, and the corallum is gently twisted in that 

 direction. The width of the corallum in front and above is greater than 

 at any other part, and it becomes narrower towards the third angle. 

 The width of the calice is very small in comparison with its length. 



Corallum narrow and long, low, and generally triangular, present- 

 ing the appearance as if the anterior end were the original turbinate 

 coral, which has since grown posteriorly only. "Wall well developed, 

 imperforate, marked anteriorly by a curved linear furrow and traces 

 of an erosion — the mark of an appendicular process. Epitheca exists, 

 very rudimentary, but is visible around the first angle and close to 

 the erosion. Calice long, narrow, slightly curved, wider in front, 



