TLATE XCIX. 



GtROCBRAS SPINOStTM. 



Page 382. 

 See Plates 47, 48. 49, 98. 



Tig. 1. Lateral view of a compreeseil specimen, preserving the chamber of habitation and about thirty air- 

 chambers, showing the curvature of the tube and the increase in the deplh of the air-chambers 

 fi"om the a]>ex to the grand chamber. The internal mould shows the bjises of two lateral i-ows 

 of semi-tubular spines. 



Fig. 2 id. A. gutta-|)ercha impi-ession of the matrix, showing the characters of the surface ornamentation 

 more clearly than is j^reserved on the internal cast. Toward the aperture the tube is orna- 

 mented by transverse expansions of the test, with the bases of the spines preserved as sinu- 

 osities of the margins. 



Vig. 3. Veoiral tiaw of two air- chambers, showing portions of the siphuncle exposed in the process of 

 weathering. 



Rg. 4. A small chambered fragment, showing the siphuncle as in the preceding. 



Fig. 5 id. A septum showing the position of the siphuncle and the transverse section of the tube, which has 

 been di8turbe<l by compression. 



Fig. 6. The chamber of habitation of a small individual associated with this species, showing its proportions 

 and the concavity of the la.st septum. 



Rg. 7 id. The septum, showing the position of the siphuncle and the transver»e section of the tube, slightly 

 disturbt-d by compression. 



Fig. 8. The septum, at the base of a large chamber of habitation, showing the transverse section of the tube. 

 This sj)ecimen and the preceding are referred with some doubt to this species, as they (W 

 not possess distinctive characters. 

 The specimens here figured are from the Schoharie giit, at Schoharie, N. T. 



