lambe. ] CANADIAN PALAEOZOIC CORALS. 1 23 



relative geological positions of the eight divisions of the limestones 

 (op. cit. p. 2) says, "The two lower divisions (1 and 2) are most probably 

 Silurian ; about the age of the Helderberg of the New York geologists." 

 In 1858 nearly fifty specimens were obtained by J. Richardson at Cap 

 Bon Ami near Dalhousie, N.B., in rocks of the same age ; these show the 

 decided cancellation of the surface and the periodic annular swellings, as 

 well as in many instances the basal extremity which is quite pointed and 

 sometimes has a scar of attachment preserved. 



Zaphrentis incondita, Billings. 



Zaphrentis incondita. Billings. 1874, Pakeoz. Foss. vol. II, pt. I, p. 7, pi. I, figs. 1, 

 la, lb, 2, 2a, 2b. 



" Corallum simple, turbinate and strongly curved at the base, becoming 

 cylindrical above ; nine or more inches in length and over two inches in 

 diameter. From the acute base upwards it expands to a thickness of 

 about fifteen lines in a length of two inches, and to twenty-four lines, in 

 four inches ; above which the body of the coral becomes more nearly 

 cylindrical, or only very gradually increasing in diameter. Surface with 

 numerous engirdling ridges of various siz^, the larger are from half a 

 line to five lines in width, and are often angular on their crests. Upon 

 these larger ridges and in the grooves between them are numerous smaller 

 ridges, or transverse striae, generally two or three in a width of one line. 

 The longitudinal, or septal striae, are in general only obscurely seen, 

 beins; obliterated by the transverse grooves ; there are five or six of them 

 in the width of three lines. 



"In the interior of the coral, the radiating septa reach the centre in 

 the basal portion. But, above a diameter of one inch, there is a large 

 space in the centre occupied by the transverse diaphragms alone, the 

 septa not extending more than half an inch inward. Tlnre are two sets 

 of them, the smaller projecting inward rarely to the depth of one line. 

 There is one of the smaller between each two of the longer. 



"The transverse diaphragms are well developed. They are much un- 

 dulated in the central portion and strongly curved downwards near the 

 exterior. There appear to be ten or twelve of them in the length of one 

 inch ; but owing to their undulations, there are sometimes places in 

 which they are separated to the distance of two or three lines, while 

 elsewhere they may be nearly in contact. The septal fossette has not been 

 observed. 



" Varieties. — Occurring along with the above is a somewhat more 

 slender form with, in a general way, the same external characters, but 

 with the transverse diaphragms more regular and the septa extending in- 



