158 NEW YORK STATE MUSEUM 



Textularia trochus d'Orbigny 



Plate I, figures 9, 10a, b 



Textularia trochus d'Orbigny, 1840, Mem. Soc. Geol. France, 4: 



45, pi. IV, figs. 25, 26 

 Textularia trochus Jones, Parker & Brady, 1865, Pal. Soc, 19: 150, 



pi. iii, figs. 17, 18 

 Textularia trochus Vad^sz, 1910, Triasforam. aus dem Bakony, 



p. 14, pi. I, fig. 5 and fig. 2 in text 



The transverse section shown by Vadasz (loc. cit.) to illustrate the 

 arrangement of the segments could easily be used for a drawing of 

 our specimen of this large Textularia found on slide 5 (X) . 



The shell is short, stoutly built and of coarse construction, very 

 different from the many minute delicate and beautiful Textularia 

 globulosa found in these cherts so abundantly. The segments 

 offset somewhat alternately as if not truly apposed, the hollow 

 cavity within dovetailing above and below each chamber. The 

 sutures are almost flush and the chambers are narrow and horizontal, 

 not arched as in many other Textulariae. This is one of the most 

 symmetrical of all the genus and widens rapidly but very symmetri- 

 cally from a rather blunt base which in some forms draws down to 

 a rather sharp extremity. There are but few segments, apparently 

 about seven or eight in our specimen in each series, but those at the 

 distal end are indistinct. The length of this specimen measures 

 0.35 mm. The oral end is centrally depressed and the entire form 

 may lack another chamber, but probably does not as the section 

 seems pretty evenly cut. The walls are very thick except on the 

 border and along the central portion of the shell. 



This form must have been finely arenaceous, as it has such a coarse, 

 massive structure and is so very different from the Textularia 

 globulosa Ehr. with its hyaline appearance. The Trias forms 

 figured by Vadasz were twice the size of this chert specimen and 

 measured in length 0.60 mm. This form occurs in the Cretaceous 

 rather frequently as well as in many Tertiary deposits. Jones 

 reports the species as having wide distribution in existing oceans in 

 shallow waters, especially among coral sands. 



There are three Textulariae which are rather closely allied to 

 Textularia trochus, namely T, turris, T. conic a, 

 and T. barretii, but the last is much more elongated with 

 labyrinthic interior, T. turris is more coarsely constructed as 

 well as more elongate, while T. c o n i c a is very short, more or less 

 compressed and the walls are thin. There is also some difference in 



