ON THE STRUCTURE OF CARBONIFEROUS-LTMESTONE CORALS. 481 



curved spines which are attached to the crown of the costiE. They are 

 round, and attached to the costfc by a broad, expanded base. The " ball- 

 and-socket " process alluded to by Dr. Duncan wc have failed to discover. 

 Fig. 40 C is a transverse section of the same, nat. size. 



Figs. 7, 9, 10, 11, 13, 16, 17, 18, 23, 24, 25, 27, 29, 30, 32, 33, 34, and 

 35 exhibit structural characteristics hitherto unnoticed. Several of these 

 forms may be seen in many of our museums and private collections named 

 as Ci/athropsis and Zaphrentis ; but in structure they have no characteristics 

 common to either of these genera. 



Figs. 21, 38, 40, 41, 42, and 43 are typical specimens of HeteropliyUia, 

 described by Dr. Duncan in the ' Transactions of the Royal Society ' for 

 1867. 



Plate V. contains six varieties of genus Clisiopliyllum. 



Fig. 1 represents the external aspect of CUsiophyllam Keyserlingi. This 

 species is distinguished by the lamellae curving round, and ascending to 

 the crown of the large conical boss that fills up the centre of the calicular 

 cavity. Fig. 1 A is a transverse section of the same. Fig. 1 13 exhibits a 

 longitudinal section, with the columellarian line passing down the centre 

 of the coral. 



Figs. 3, 3 A, 3 B, and 3 C belong to the same species, and represent the 

 structures from the earliest to the mature state of development in any 

 normal specimen. 



Fig. 6 is a transverse section of the largest specimen of the same that has 

 come under our observation. 



Figs. 2, 4, and 5 are closely allied species, if not varieties. 



Figs. 9, 11, 12, and 13 are distinct species, and illustrate a previous 

 observation, viz. that specific identification cannot rest on the mere niim- 

 ber of the lameUse filling up the columellarian space in the centre of the 

 ealice. 



Fig. 12 A is 15 lines in diameter, and has twenty-seven lamella}. 



Fig. 11 is only 6 lines in diameter, and has thirty-seven lamelltc filling up 

 and forming the conical boss in the centre of the ealice. 



Figs. 7, 8, and 10 are distinct genera. These forms, before being cut, 

 were classified as genus Cl'mophylUim ; but the transverse sections iiresent 

 no characteristics in common with that genus. They belong to a genus 

 quite distinct, and as yet unnamed. 



Plate VI. contains representations of three species of Lonsdcdlui. 



Fig. 1 represents a longitudinal section of LonsdaUia ruyosa. Figs. 1 B 

 and 1 C exhibit the young coralUtes in their different stages of development. 



Fig. 2 is a transverse section of the same species. In this section we have 

 delineated the growth from the ovular germ through the different stages of 

 development to the mature coral. In one stage the embryo coral is seen 

 passing from the interseptal locula ; in another it is seen semicircular in 

 outline, and just outside the epitheca. In some it is circular in outline, 

 whilst others exhibit the full development of the septa. Fig. 2 A is the 

 same species, enlarged six diameters. 



Fig. 3 represents LonsdaUia duplicata. 



Fig. 4 A is one of the corallites enlarged, with a young corallite attached 

 to the epitheca, exhibiting the development of the primary septa, which, in 

 the maturer forms, is seen to fill up the columellarian space. 



It wUl thus be seen that we wish to avail ourselves of every fact, and to 

 delineate the most deUcate structures. To accomplish the latter, our peculiar 

 process is well suited. We may thus assist the student and beginner in 



1873, 2 1 



