580 PROCEEDTNGS OF THE NATIONAL MUSEUM. vol. xxvi. 



Hojiotrypa frondosa belongs to the typical group of the genus and 

 should be compared with IL jiaheUark. The flabellate growth, large 

 rounded monticules, few acanthopores, and the presence of both dia- 

 phragms and cystiphragms in the peripheral region are characteristic 

 features. 



Occut'^'ence. — Rare in the Warren beds of the Lorraine formation in 

 Indiana and Ohio. Harmans Station, Indiana, is the type localit3^ 



HOMOTRYPA FLABELLARIS Ulrich. 



Homotrypa flahellaris Ulrich, Geol. Surv. Illinois, VIII, 1890, p. 411, pi. xxxii, 

 3-3c. 



This species with its varieties has quite a range, both geologically 

 and geographically, specimens being found, generally abundantly, in 

 the Lorraine and Richmond at many localities in the Mississippi 

 Valley. The species was described from specimens found in the 

 Richmond at Wilmington, Illinois. The figured sections illustrating 

 the internal structure were prepared from a colony in which the 

 mature region was not fully developed. Mature specimens show a 

 moderately crowded series of cystiphragms and diaphragms in the 

 peripheral region. If the large acanthopore was omitted from our 

 fig. 14, on Plate XXI, it would shoTv the characters seen in a vertical 

 section of this species. The specific characters are the flabellate 

 growth, smooth surface, nine zooecia in 2 mm, few small acantho- 

 pores, mesopores tabulated, numerous in the maculae and not uncom- 

 mon among the ordinary zooecia, a moderate number of diaphragms 

 in the axial region and a well-developed series of diaphragms and 

 cystiphragms in the peripheral region. 



Occurrence. — A common species in the Lorraine and Richmond 

 formations of Illinois, Indiana, Ohio, Kentucky, Tennessee, and 

 Wisconsin. 



Cat. Nos. 40217-40223 Harris collection, 41 772, 41774-41777, 41780- 

 41782, U.S.N.M 



HOMOTRYPA FLABELLARIS var. SPINIFERA, new variety. 

 Plate XXI, figs. 11-15. 



This variety agrees with II. Jlabellaris in all essential characters 

 save one, namely, that at rather regular intervals among the zooecia 

 very large acanthopores are developed, the place of a zooecium often 

 being occupied ])y one. This gives the otherwise smooth surface of 

 the zoarium a spiny aspect. The acanthopores often originate in the 

 axial region and proceed to the surface irrespective of the course of 

 the zooecia. 



Occurrence. — Abundant in the Fairmount beds of the Lorraine at 

 Cincinnati, Ohio, and vicinity, and in the Richmond at Richmond, 

 Indiana, Oxford and other localities in Ohio. 



Cat. Nos. 41773, 41778, 41779, 41783, U.S.N.M. 



