5.1323. STRUCTURAL FEATURES OF HOMOTRYPA—BASSLER. 587 



kth moderately thick walls, about nine in 2 mm. Acanthopores not 

 iresent at the surface and usually also absent in sections. Diaphragms 

 bsent in the axial region, appearing in the transitional zone to the 

 Peripheral region and increasing in number toward the surface. 

 H'stiphragms in a moderately crowded series in the peripheral region. 

 ' The well-developed diaphragms and cystiphragms and the almost 

 omplete absence of acanthopores, together with the growth and sur- 

 lace features, characterize this species. The specific name is in honor 

 \i Mr. John M. Nickles, who collected the species. 



Occurrence. — Rather abundant in the Richmond at Ray wick, 

 lentucky. 



1 Cat. No. 34328, U.S.N.M. 

 i 



HOMOTRYPA GELASINOSA Ulrich. 



[ Homotrypa gelasinosa Ulrich, GeoL Surv. Illinois, VIII, 1890, yi. 411, pi. xxxii, 

 ' 2-2d. 



The very pronounced elongate maculae characterize this species. In 

 j;rowth and general characters it is near JT. Jlabellaris, but the smaller 

 ooecia, of which there are ten in 2 mm., few acanthopores and elongate 

 iiacute, separate it from that form. The nearest relative is probably 

 T. nitida, which see for comparison. 



Occurrence. — Rare in the Richmond, at Wilmington, Illinois. 



Cat. No. 41770, U.S.N.M. 



HOMOTRYPA SPLENDENS, new species. 

 Plate XXV, figs. 11-14. 



Zoarium liabellate, an average example measuring 4 to 5 cm. in 

 leight, 3 to 4 cm. in width, and 3 to 4 mm. in thickness. Surface 

 vith strongly elevated monticules, 2.5 to 3 mm. apart, measuring 

 rem center to center. Apertures varying from subpolygonal to sub- 

 Ircular, with very thick walls, about seven in 2 mm. Acanthopores 

 ppareutl}^ wanting. In the axial region the walls are very thin and 

 he diaphragms rather numerous, averaging a little more than their 

 liameter apart. In the peripheral region the walls are very much 

 hickened and both cystiphragms and diaphragms are abundant. 



This splendid species, with its large cells and thick walls, requires 

 10 detailed comparison with other forms. The associated II. flahellarls 

 •Gsembles it in zoarial growth, but the ditference in the size of the 

 ■ells of the two species can be seen with the unassisted ej^e. Sections 

 how that a great deal of calcareous tissue is deposited along the tube 

 vails and even on the cystiphragms. This accumulation often obscures 

 he cystiphragms and the boundaries of the cells. The unusual thin- 

 less of the walls in the axial region is in marked contrast with their 

 'reat thickening in the peripheral region. The apparent absence of 



