518 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 





the present form the two portions are most distinctly marked. The 

 extreme variation in the length of the narrow proximal portion is 



noted above, and is indicative of 

 a the fact that this part of the zooe- 



cium is the least stable in simple 

 species of Cyclostomata. 



Occurrence. — The American 

 specimen illustrated in figure 16, 

 upon which the species is based, 

 incrusts a fragment of RJiyncJio- 

 trema cajMX and was found in the 

 highest beds of the Maquoketa 

 shale division of the Richmond 

 group at Iron Ridge, Wisconsin. 

 The Russian example assigned to 

 the species (fig. 17) was found at 

 Kertel, Island of Dago, in the 

 Lyckholm limestone, associated 

 with Calapoecia crihriformis Nich- 

 olson, Holy sites sp., Streptelasma, and other fossils known to occur in 

 certain strata of the Richmond group in America. 



Holotype and paratype.—Csit. nos. 54173, 57109, U.S.N.M. 



CORYNOTRYPA CURTA, new species. 



This rather unique species grows usually in crowded little masses 

 of zocBcia, which, at first glance, show slight resemblance to the 



Fig. 17.— Coetnotkypa abeupta. a and h, poe. 



TION OF A ZOAEIUM, X9 AND X20, INCEUSTING A 

 CEENOID COLUMN. EAELY SILUEIAN, LYCKHOLM 

 FOEMATION, KEETEL, ISLAND OF DAGO, BALTIC 



Sea. 



Fig. 18.— Coeynoteypa cueta. a and &, poetion of a ceowded zoaeium, X9 and X20, inceust- 



ING THE BEYOZOAN LlOCLEMELLA SOLIDISSIMA ; C, FEAGMENT OF A ZOAEIUM GEOWING MOEE NOE- 



MALLY, X20. Richmond geoup. Savannah, Illlnois. 



dehcate, graceful colonies of other members of the genus. Upon 

 resolving these small zoaria into their component zocecia, it becomes 



