OF WESTERN STND. 185 



in consequence of the pairs of pores being wider apart midway upon the petal than at 

 the extremities. The inner pores are round, and the outer pores elongate or comma- 

 shaped ; with the connecting furrow very narrow and difficult to make out, and often 

 appearing to be obliterated before reaching the inner pore. The divisional septa are 

 broad, and ornamented with one or two primary tubercles in sunken scrobicules, rather 

 smaller than those in the interporiferous area. The interporiferous area is nearly equal 

 to twice the width of the poriferous zone at its widest part ; it is ornamented with rather 

 smaller primary tubercles than those upon the iaterradial plates of the test. The odd 

 anterior ambulacrum terminates at a short distance before the tumid rounding of the 

 margin commences. The antero-lateral petals are much shorter than the odd anterior 

 one, and are a shade narrower at their widest part. On the outer half of their 

 poriferous zones the distance which separates the pores of a pair commences to 

 diminish more rapidly than in the odd anterior petal, in consequence of which the 

 line of the outer pores forms a much more rapid curve, which causes the petal to have 

 a more contracted appearance. The interporiferous area is narrower than in the odd 

 anterior petal, and is somewhat more contracted at the outer extremity, hence the 

 poriferous zones are much closer together in the antero-lateral petals. The postero- 

 lateral petals are about equal in length to the odd anterior petal, and are consequently 

 longer than the anterior pair, with which, however, they correspond in breadth. The 

 poriferous zones do not contract in width so rapidly as in the anterior pair, and the 

 anterior zone of each postero-lateral petal usually appears to be somewhat broader than 

 the companion zone of the same petal. The postero-lateral petals terminate about 

 midway between the apical disk and the margin ; whilst the antero-lateral petals extend 

 very slightly beyond the same proportional distance, the space beyond the posterior pair 

 being obviously much greater. 



The ornamentation of the interradial portions of the abactinal area is very uniform, 

 and consists of small primary tubercles, sunken in deep small scrobicules, closely placed, 

 and with the intermediate portions coalesced or confluent. On the actinal surface the 

 tubercles and the scrobicules become larger as they approach the mouth, and the former 

 are distinctly perforate. Along the median interradial line in the posterior interradium 

 there is much of the deep-pitted ornamentation characteristic of this genus. 



The peristome is large, pentagonal, and longitudinally elongate. It is excentric in 

 front, placed beneath the apical disk, and presents a well-developed floscelle. The 

 bourrelets are subequal, large, deep, conspicuous, and rather angularly subtubercular 

 externally, their whole surface covered with fine uniform granulation. The phyllodes 

 are wide and well developed. They consist of a curved outer line of pores, six to eleven 

 in number, the outline of the phyllode being somewhat lyre-shaped, and an inner series 

 of four to five pores to each zone standing in a more or less straight line ; and inside the 

 lines of inner pores are a corresponding number of spheeridia-pits, each companion pore 

 and pit being separated from the neighbouring pair by a more or less developed costal 

 ridge. Indistinct ridges are present in connexion with the series of outer pores. There 

 is a very narrow but distinct channel between each bourrelet, and a pore is present at 

 the outer extremity of each of the long, delicate peristomial plates. The odd anterior 



