51 



Family NAUTILIDiE. 



SOLENOCHILUS HENRYVILLENSE, n. sp. 



Plate IV, Fig. 4, lateral view; Fig. 5, dorsal view and transverse 

 section, the black spot may not be the siphuncle; 

 Fig. 6, ventral view. 



Species medium size, judging from our incomplete specimen. 

 Shell subglobose. Whorls expand laterally much more rapidly than 

 they do dorso-ventrally. Umbilicus small, deep, perforated. Margin 

 of the umbilicus abruptly rounded. Our specimen preserves two 

 volutions, but a complete shell may have three or more. The volu- 

 tions are deeply embracing, showing only a small margin in the 

 umbilicus. In the early growth of the shell, a transverse section, 

 disregarding the dorsal sinus is subquadrangular, but later, a trans- 

 verse section becomes subovate. The lateral surfaces are flattened, 

 and converge toward the ventral side. The ventral side is, in early 

 life, depressed convex, but later, becomes sharply rounded. Septa 

 only moderately concave, and increase their distance apart with the 

 growth of the shell ; but not so rapidly as the shell expands. The 

 sutures have broad ventral and lateral lobes with saddles at the ventro- 

 lateral and dorso-lateral angles. 



A little of the outer shell is preserved on our specimen and it is 

 thin, but no surface ornamentation is preserved. The living chamber 

 is unknown. What appears to be the siphuncle is on the ventral 

 side of the center, and our specimen has two chambers broken so as 

 to show smooth septa, at the ventral margin, without any evidence of 

 a siphuncle near the ventral margin, where it usually occurs in this 

 genus. 



This species is so different from S. collectum, which it may be said 

 to most resemble, that a comparison is unnecessary to distinguish it, 



Found by G. K. Greene, in the Knobstone Group, near Henryville, 

 Indiana, and now in the collection of Wm. F. E. Gurley. 



