ROBERTS — UPPER SII-URIAN CORAI^S. 57 
VQg, crowd upon each other's limits, and a mass of corallitcs is the re- 
sult, whoso base is the old parent coral, and whoso upper surface is 
colored by the star-rayed cups of the children. Acervularia cmanas 
is the commonest species of these family corals. 
The polyps that formed these cup-corals grew from their base up- 
wards, and were probably long livers, for a well-matured specimen of 
Cijathophi/llum Loveni will measure five inches in height, indicating 
by the number of prominent edges that surround it — accretion- 
wrinkles they are called — ^a long and chequered existence ; for when 
these are regularly prominent, we infer the polyp led an active life of 
development. On the contrary, when their irregularity forms annu- 
lar depressions on the coraUum, these indicate the occasional repose 
of the zoophyte from its work of extension. 
The common species belonging to these cup-corals are easily 
known. Cyathophyllum Loveni has very prominent accretion- 
wrinkles, while upon the sides of C. angustum they are but feebly 
developed. C. pseudoceratites has an oval calice, with only thirty- 
eight large septa alternating with a Like number of smaller ones ; the 
two former species have sixty of each kind. Omphyma turbmata is a 
short, wide-mouthed species, with double the number of septa, and 
has radiciform appendages, i.e., rootlets, attached to its lower end. 
0. suhturbinata differs only in being taller, as its name implies, 
having but eighty septa, and well developed accretion-wrinkles. 0. 
Murchisoni is nearly alhed, but has vesicles, or bladder-like tubercles, 
coming up among the septa. Then there is Ooniophyllum Fletcheri 
with a square calice ; Aulacophyllum mitratwm, a small turbi- 
nated cup, whose principal and rudimentary septa combined only 
amount to sixty-eight, and Ptychophyllum patellatum, with one hun- 
dred septa, and the border of its calice so much raised that the coral- 
lum resembles the cap of a mushroom. These are all the simple cup- 
corals we are likely to meet with in the Wenlock rocks. Among the 
composite ones is the species I before alluded to, Cyathophyllum arti- 
culatnim, generally met with as a mass of tall slender corallites, so 
thin-skinned that their upright internal lines of structure (costce) are 
clearly visible. Syringophyllum orgamim is another, having star- 
headed tubes of exquisite beauty ; and as a connecting link between 
this and the next division of cup-corals, we have Acervularia luxu- 
vo^. III. H 
