PLATE CXXIV. 



< '\ KTOCERAS CITUM. 

 Page 36. 

 Pig. 1. A specimen retaining the test ami its ornamentation over the entire exterior of the tube. 



Upper Helderberg limestone. LeRoy, Genesee county. 

 Pig. '-'. The internal mould of an individual, showing the revolving furrows of the erennlations. and the 

 transverse markings correspo i ling to the foliate expansions of the test. 

 Dpper Helderberg limestone, Falkirk, Urit county. 

 Fig. 3. The retral sinus in the expansions of the test, as shown on the convex or ventral Bide of a speci 

 men. This figure is taken from a gutta-percha impression of a natural mould ami enlarged 

 two diameters. 



Upper Helderberg limestone. Cayuga, Ontario, Canada 



Gyroceras Nereus. 



Page 36. 

 Pig. 4. \n enlargement to two diameters, of the ornamentation of the test on the ventral side of the tube, 

 showing a marked difference in the sinus of the ornamentation from that represented in figure 

 8 of this plate. 



Corniferous limestone. (' lurry Valley, Otsego county. 



Gyroceras laciniosum. 



Page 3G. 

 Fig. 5. Lateral view of the specimen, showing the curvature of the tube ami the transverse ridges corre- 

 sponding to the ornaments of the test. The matrix preserves the characters and shows the ex- 

 tent of the fimbria.. 

 Fig. >i. Id. Outline, showing the transverse section of the tube. 



Corniferous limestone. Cherry Valley, Otsego county. 



Cyrtoceras Jason. 



Page 36. 

 Fig. 7. Lateral view of the internal mould of a large individual, showing the transverse ridges and rows 

 of nodes corresponding to the expansions and tubular spines of the test. Several of the trans- 

 verse lamellae are seen in the matrix adhering to the dorsal side of the tube. 

 Schoharie grit. Clarksville, Albany county. 



