438 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 6, 



the lower part of the base being curved in the direction of the great 

 axis ; pedicel very slender. Epitheca well developed, pellicular, and 

 permitting the costas to be seen ; it is in more or less transverse wavy 

 ridges, and it ceases two or three lines below B the horizontal calicular 

 margin. Wall very thick and dense. Costse : the larger are all nearly 

 equal ; the smaller correspond with the rudimentary septa, and are 

 continued down between the larger, gradually merging into a row of 

 rounded granules as the epitheca covers them : the larger are to be 

 traced more or less to the pedicel; they project but little at the cali- 

 cular margin, and are rounded ; where the epitheca commences they 

 become flatter, and are sparsely granular, the granules being really 

 dentations in one series ; shortly, however, the granular appearance 

 is lost, and a ridged fcg-m is seen, some of the lateral costse evidently 

 uniting with others a little above the pedicel ; they are close, but 

 not crowded ; many are parallel, and never crested nor sharply spined. 

 Calice with its margins a little sinuous, very long, narrow, and a 

 little curved, the long axis on the same plane as the short. Fossa 

 deep and narrow. Septa very numerous, barely exsert, rounded at 

 the wall, and a little thicker there than elsewhere; often a little 

 curved, extending well inwards. Except the rudimentary septa, 

 which correspond to the short costse, the septa are subequal, and the 

 principal are not easily recognized ; generally one is large, and the 

 next smaller ; they are rounded above, and are nearly perpendicular 

 at their inner margin ; free margin not incised ; lamellae granular. 

 The granules, which are conical and large, form linear series, which 

 are directed from below inwards and upwards. Septa in six systems 

 of at least six cycles. There are forty-three septa to an inch. Colu- 

 mella essential, lamellar, attached to the septa by trabecular passing 

 at right angles from it ; its surface is very long, and it probably was 

 sharp ; above the free surface there is a deep, linear, calicular fossa. 

 Pali as delicate rounded lobes, barely to be recognized, attached to 

 the usual lamina? ; the granules of the pali form series parallel to 

 their circular outline. Endotheca none. Height \\ inch ; length of 

 calice 3^ inches ; breadth 9 lines ; depth of fossa 4 lines, of inter- 

 septal loculi much more. 



This interesting simple Coral was discovered in Jamaica by the 

 late Mr. Barrett, with whose memory I associate it. 



Jamaica ; varieties in San Domingo. Brit. Mus. 



2. Placotkochus alveolus, spec. nov. PL XYI. figs. 2 a, 2 b. 



Corallum simple, very long, low, and narrow; trough-shaped, 

 rounded at the extremities, by one of which it was attached ; trans- 

 verse outline triangular. Wall very thick, stout at the calicular 

 margin, covered close up to this by a dense epitheca, which shows 

 traces of the costae tolerably distinctly above, where they are repre- 

 sented by a series of granules, and less so below, where they are 

 simple elevations on the wall; all the granules are microscopic. 

 Sides of the wall more or less wavy. Between the semicircular 

 margin of the calicular end and the base there is a circular hole 

 with irregular and rounded lips — the " erosion." This lateral 



