14 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 5, 



more rounded than in that species ; and the part which is connected 

 with the umbilicus is composed of a larger number of dentations. 



Of this species I have been able to examine one perfect specimen, 

 which is probably adult, and is but 6 centimetres in diameter. The 

 height of the mouth is about 3 centimetres, and the width 1 centi- 

 metre. The diameter of the umbilicus is also 1 centimetre. It forms 

 part of the series in the Museum of the Geological Society of London. 

 Prom the Productus-limestone of Vurcha. 



35. Ceratites Lawrestcianus, De Kon. PL VI. fig. 3. 



This fine species is remarkable on account of the form of the lobes 

 and saddles which bound the chambers. Its general shape is that of 

 a flattened disc whose margin is rounded. Its surface appears to 

 have been smooth, the test not having left any trace of striae or fur- 

 rows on the internal cast, which is all I have here to describe. The 

 spiral coils are strongly overlapping, and leave but a very small um- 

 bilicus. The dorsal lobe is very large, and divided into two by a 

 small median saddle ; it is much less deep than the lateral lobes, but 

 its width and indentations, which are five or six in number, strongly 

 resemble those of the last lobes ; it is connected with the upper lateral 

 lobe by a slightly elevated saddle, narrow and rather acute : the in- 

 ferior lateral saddle is, on the contrary, very high, but much more 

 wide at its base than the former, and but little elevated ; it is con- 

 nected with the margin of the umbilicus by seven or eight indenta- 

 tions, which assume the character of auxiliary lobes. 



I am acquainted with no species with which this one is compa- 

 rable, unless it be the C. Davidsonianus, which differs from it in the 

 much more rounded shape of its saddles. 



The approximate number of its chambers is about thirty ; the 

 total diameter is 10 centimetres, and that of the umbilicus 14 milli- 

 metres: the height of the last whorl of the spire is 5^ centimetres, 

 and its thickness about 3 centimetres ; whilst the height of the pre- 

 ceding coil is but 28 millimetres, and its thickness 18 millimetres. 

 The distance which separates the back of the last coil but one of the 

 spire from that of the last is 3^ centimetres. 



36. Gontatites ? Gangetictts, De Kon. PL V. fig. 2. 



I have placed this species among the Goniatites for the sole reason 

 that I have been unable to discover any indentations on the edges of 

 the lobes or chambers. It is highly probable that the denticulations 

 have been destroyed by the atmospheric agencies to which the speci- 

 men had been exposed. This species is rather strongly compressed 

 and phnorbiform ; its first spiral whorls are only half overlapped by 

 those that succeed them. The umbilicus is wide, and its diameter is 

 equivalent to about one-third of the entire diameter of the shell ; its 

 back is very convex, and the surface appears to have been smooth. 

 The number of its chambers is from twenty to twenty-two ; their 

 height is about twice their width : the dorsal lobe is divided into two 

 by a little prominent linguiform septum. The lateral lobes are nar- 

 rower than the saddles which produce them ; both are rounded, and 



