CORALS FROM THE UPPER CHALK. 51 



Those of the second order are nearly as large as those of the first set, and thus produce the 

 appearance of twelve tertiary systems. Height, from one to two inches ; diameter of the 

 calice five lines ; its depth, two lines. 



This species is easily distinguished from all the other Parasmilia by the great develop- 

 ment of its columella, which occupies nearly half the diameter of the calice, and by the 

 spongy structure of this organ. It most resembles P. centralis, from which, however, it 

 differs also by its thick form and the greater development of the tertiary costse towards 

 its basis. The breadth and delicate granulations of the costae may equally serve to dis- 

 tinguish it from P. Gravesiana, P. dongata, P. cylindrica, and P. Mantelli. It differs 

 from P. serpentina by having an additional cyclum of septa, and by its basis not being 

 smooth, as is the case in the latter. 



This fossil is found in the upper chalk of Norwich, and exists in the collections of the 

 Geological Society, of the Geological Survey, and of the Museum at Paris. It appears 

 probable that it has often been confounded with P. centralis, and that some of the figures 

 referred to that species may in reality belong to it; but the engravings here alluded to are 

 not correct enough to enable us to decide this question. 



5. Parasmilia (?) serpentina. Tab. VIII, fig. 3, 3 a, 3 b. 



It is not without some doubts that we place this fossil in the genus Parasmilia, for in 

 the unique specimen that has come under our observation, the calice was in so bad a state 

 of preservation that it was impossible to decide whether the papillae seen near the centre of 

 that part were fractured septa or remains of pali, or even trabiculae belonging to the 

 columella. However, the first hypothesis appears most probable, and the general appear- 

 ance of the corallum is also very similar to that of all the other Parasmilia. 



This fossil is almost cylindrical, slender, much elongated, and bent ; it presents some 

 strongly marked circular constrictions, indicative as usual of a certain intermittence in 

 the progress of its growth. The costae are narrow, straight, rather unequal alternately, 

 scarcely distinct near the basis, but more prominent towards the upper part of each inflated 

 ring and near the calice ; the calice is circular. The septa form three complete cycla and 

 are rather closely set, exsert, and somewhat dilated exteriorly. The columella is well 

 developed. Length, one inch, seven lines. Diameter of the calice, two lines and a half. 



This coral, belonging to Mr. Bowerbank's collection, was found in the upper chalk at 

 Bromley, in Kent. 



It is the only species of Parasmilia in which the fourth cyclum of septa does not exist ; 

 it is also characterised by its basis not being costulated. 



