MADEEPOEAEIA OF THE DEEP SEA. 321 



fourth, which are usually rudimentary, are absent. The primary and the secondary 

 septa are nearly equal in size, and are large, projecting, exsert, thin, and marked with 

 distinct granules. The secondary septa are not so high as the primary. The tertiary 

 septa are smaller and less exsert than those already mentioned, and they usually unite 

 to the secondary near the false columella. 



The columella is formed by processes from the ends of the larger septa. 



The interseptal spaces are broad and shallow. 



The costae are more numerous than the septa. The primary and secondary costse are 

 slightly prominent at the calicular margin, and may be traced to the fine peduncle. 

 The third and fourth orders are less so ; and there are some traces of a fifth cycle in 

 the form of wavy rows of granules or ridges. 



The height of the corallum is -^ inch ; and the breadth of the calice is -^^ inch. 



Dredged up in No. 16 dredging, second expedition of the 'Porcupine,' and in 

 994 fathoms. 



I have named this new Turbinolian genus after Sir Edward Sabine, K.C.B., the 

 President of the Eoyal Society, 



Genus Desmophtllum, Ehrenberg. 



Desmophtllum crista-galli, Milne-Edwards and Jules Haime, 1848, oj). cit. (Plate 



XLI. figs. 10-16.) 

 DesmophyUum dianthus, Ebrenb. 1834. 



a. cumingi, Milne-Edwards & Jules Haime, 1848, op. cit. 



|3. costatum, Milne-Edwards & Jules Haime, 1848^ op. cit. 



If the variations of the typical form of this species are studied, it will be noticed that 

 there are great differences in the position, size, and continuance of the costae, in the 

 exsertness and granulation of the septa, in the height, compressedness, and size of the 

 base of the corallum, and in the granular ornamentation of the outside of the wall in 

 different specimens. The recognition as varieties of the forms marked a and /3, instead 

 of species, is necessary. 



The size, costal development, exsertness, and granular condition of the ornamentation 

 of the septa and outside of the corallum depend upon the age and nutrition of the 

 specimen. Very thin septa are not so granular superiorly as those of corallites which 

 have very dense walls and thick septa ; and the costaj of the latter kind are usually 

 most prominent. 



At great depths, 994 fathoms, No. 16 dredging ; and where the Madreporaria appear to 

 be very abundant the specimens of DesmophyUum are usually very granular externally ; 

 moreover they become attached to compound forms of corals, and both have the same 

 ornamentation, so that it is difficult not to believe in the DesmophyUum being part and 

 parcel of the growing mass. They are especially liable to be joined to branches of the 

 fistulose bifurcating coral which will be described further on [SolenosmiUa varialUis). 



2z2 



