No. 1797. 



NEW TUBULIPOROID BBY0Z0A—BAS8LER. 



519 



evident that the crowded effect is produced by frequent budding of 

 the short, ahnost rounded cells. A portion of such a dense growth is 

 illustrated in figures 18a., h. Occasionally specimens with simple 

 strings of zooecia are found, and these show the intimate relationship 

 of C. curia to the more common C. injlata. 



Further comparisons with C. injlata will show the following differ- 

 ences: In C. curta the stolon is practically entirely absent, the 

 zooecium is small, but its angle of divergence is so great (70°) that the 

 outline is subcircular or broadly oval. C. injlata has a larger and 

 more pyriform zocecium, a distinct although short stolon, and a 

 much* smaller angle of divergence (40°). The other species of the 

 genus are less closely related and will not need detailed comparison. 



The measurements of a normal zooecium in C. curta are: Length, 

 0.33 mm.; greater width, 0.26 mm.; angle of divergence, 70°; six 

 zooecia in 2 mm. 



Occurrence. — Not uncommon in the upper beds of the Maquoketa 

 shale division of the Richmond group at Savannah, Illinois, 



Cotypes.—Csit. no. 54171, U.S.N.M. 



CORYNOTRYPA MEDIALIS, new species. 



The specimens upon which this species is based occur in the Rich- 

 mond formation, associated with typical examples of Corynotrypa 

 turgida and C. injlata. This associ- 

 ation, in connection with the fact 

 that the characters of C. medialis 

 are intermediate between the other 

 two forms, might give rise to the 

 idea that the three are merely mu- 

 tations of a single species. Such 

 an idea is disproved, first by the 

 constancy in the size of the zooe- 

 cium proper in each species, and 

 second by the practical identity of 

 the angle of divergence in separate 

 individuals of the same species. 

 The zooecium of C. turgida is so 

 much larger than that of C. injlata 

 that one of intermediate size is 

 still distinct enough to be easily recognized as different from each 

 with even a low power hand lens. Normal zooecia of these three 

 species are contrasted in figure 14, while a portion of the specimen 

 selected as the holotype is figured above. The variable length of 

 the stolon is shown in figure 19a, although a greater variation may 

 be expected on other examples. 



The dimensions of the usual zooecium of C. medialis are as follows: 

 Length of expanded portion, 0.50 mm.; greatest width, 0.26 mm.; 



Fig. 19.— Coetnotrypa medialis. a, a part 



OF THE TYPE-SPECIMEN, X9, INCRUSTING A 

 CYSTID PLATE ; 6, SEVERAL ZOCECIA OF SAME, 



X20. Richmond group, three miles north 

 OF Spring Valley, Minnesota. 



