110 UROCOPTIS. 



In the subgenus ARANGIA the radula is unknown. 



Subgenus IDIOSTEMMA. In U. perlata (pi. 61, fig. 18) the 

 formula is 9.1.9 ; in U. lateralis (pi. 61, fig. 17), 8.1.8. In both 

 the central tooth is quite narrow, its cusp decidedly smaller 

 than the ectocones of the adjacent lateral teeth. The meso- 

 cones of the outer teeth are very oblique in U. perlata. The 

 number of teeth in a transverse row, 17 to 19, is less than in 

 any other group of Urocoptis except some forms of Gongylo- 

 stoma. In the section Maceo, U. interrupt a has 8.1.8 teeth, 

 like those of U. lateralis in form. 



Subgenus GONGYLOSTOMA. In U. elegans, the type of the 

 subgenus, there are 12.1.12 teeth (pi. 60, fig. 8, U. e. aiiberi- 

 ana) . The central teeth are wide, as in Cochlodinella poeyana 

 and the other species of Gongylostoma, their cusps about as 

 large as those of the ectocones of the adjacent laterals. All 

 of the cusps are very large and broadly rounded. 



In the section Pycnoptychia, Binney found 8.1.8 teeth in 

 U. humboldtiana, and Fischer reports 14.1.14 in U. sctzva. 

 If correct, this indicates that the two species are less closely 

 related than their conchological characters indicate. 



In section Esocliara, U. fdbreana (pi. 61, figs. 13, 14) has 

 10.1.10 teeth. They resemble those of U. elegans in form, but 

 are larger than in any other Urocoptis examined. The cen- 

 trals are narrower than in related groups. 



U. ornata, the sole species of section Sectilumen, has 8.1.8 

 teeth in the specimen I examined (pi. 61, fig. 16), 9.1.9 in that 

 figured by Binney. Except in diminishing more rapidly in 

 size, the teeth do not differ materially from those of U. 

 elegans. 



In section Liocallonia, U. vincta (pi. 63, fig. 1) has 12.1.12 

 teeth, closely crowded and regular, with large cusps. Except 

 in standing closer, and diminishing in size only in the outer- 

 most 3 or 4, they are not unlike those of U. elegans. The 

 radula of Liocallonia as well as the shell is less specialized 

 than in Callonia. 



In U. dautzeribergiana (pi. 60, fig. 9) of the section Cal- 

 lonia, the teeth differ from those of U. elegans in having the 

 cusps narrower distally, ovate as seen from above. There 



