ON THE BRITISH FOSSIL CORALS. 153 



This species is very closely allied to Leptocyatlius elegans, Ed. & H., of the 

 London Clay. Leptocyatlius elegans has not a flat base, and it has very gra- 

 nular septa. Moreover, its costae are large and small in sets. Nevertheless 

 the alliance is of the closest kind. 



Genus Bathtctathtts. 



MM. Milne-Edwards and Jules Haime described a species of this genus in 

 their ' Monograph of the British Fossil Corals,' pt. 1. pp. 67, 68. Two spe- 

 cimens in the collection of the Rev. T. Wiltshire present all the appearances 

 recognized by those distinguished authors. The costae are very granular, and 

 not in a simple row. In one specimen the breadth of the base is very great. 



Subfamily TTJEBrNOLiN^. 



Division Titrbinoliace^. 



Genus Smilotrochus. 



Some species of this genus were described amongst the corals from the 

 Upper Greensand, and one was noticed as belonging to this geological 

 horizon which should have been included in the Lower Greensand forms. 



The Upper Greensand Smilotrochi are : — 



Smilotrochus tuberosus, Ed. ^- H. Smilotrochus angidatus, Duncan. 



elongatus, Duncan. 



There are four species of the genus found in the Gault, which are all 

 closely allied : one of them cannot be distinguished from S7nilotrochus elon- 

 gatus of the Upper Greensand. 



The specimens of this species found in the Upper Greensand are invariably 

 worn and rolled, and are generally in the form of casts ; but in the Gault the 

 structural details are well preserved, and even the lateral spines on the septa 

 are distinct. 



The Gault forms are shorter and more cylindro-conical and curved than 

 those from the Upper Greensand. 



The species of the genus Smilotrochus from the Gault are as follows : — 



1. Smilotrochus elongatus, Duncan. 3. Smilotrochus granulatus, Duncan. 

 2. cylindricus, Duncan. 4. insignis, Duncan. 



1. Smilotrochus elongatus, Duncan. 



This species was described in the first Report. 



Locality. Folkestone. 



In the collection of the Royal School of Mines. 



The lateral spines of the septa are very well marked, and the costas are 

 equal in size in this species. Its septal number varies, on account of the very 

 late perfection of the fourth cycle of septa. 



2. Stnilotrochus cylindricus, Duncan, 



The corallum is small, cylindrical, nearly straight, and has a truncated 

 base. The costae are equal, very distinct above, and rudimentary below and 

 in the middle ; they are marked with a few large granules in one series. 

 The septa are subequal, very exsert, thin, close, and marked with large 

 granules, few in number. The septa are in six systems, and there are three 

 cycles. 



Height ^ij inch. Greatest breadth rather less than j2_ inch. 



Locality. Gault, Folkestone. 



In the collection of the Rev. T. Wiltshire, F.G.S. 



