SPECIES OF CAMERIIsriDAE — BARKER 321 



last whorl in 0. catenula). The sutures are rather thick and gently 

 curved, the keel showing as a thick outer shell wall along the 

 periphery. 



O. catenula was described by Cushman and Jarvis from beds in 

 Trinidad regarded as Upper Cretaceous, showing many species in 

 common with the Velasco of Mexico. There seems little doubt that 

 the Mexican species should be referred to 0. catenula, or, if not to 

 that species, to a variety, but the original description alid figures 

 are inadequate for exact determination of the original species and 

 compai-ative material was unfortunately not available for study. It 

 has been placed in O perculinoides on account of the involute nature 

 and the rather loose coiling. In some respects it is not unlike 

 Pellatispirella but lacks the special features of the aperture and 

 construction of the shell wall of that species. 



Plesiotypes.—V.^.'^M. nos. 4978T0 and 497871. 



Occurrence. — In Mexico the species occurs in beds of doubtful 

 age, which may perhaps be referable to the Chicontepec (probably 

 Tanlajas formation of Muir). 



OPERCULINOIDES species A 



Plate 15, Figure 4 ; Plate 21, Figure 6 



Test small, compressed, completely involute. Ornamentation, if 

 present, is completely obscured by the bad state of preservation. 

 Diameter, 2.2 mm (average) ; thickness, 0.5 mm. Sections show 214 

 to 21/2 whorls, with 21 to 23 chambers in the final whorl. The septa 

 are rather thick and regularly curved throughout their length. 



In many respects this species is simila'r to perculinoides advenus 

 Vaughan and Cole, which has not been observed in the collections 

 examined. It differs from the latter, however, in having fewer coils 

 and being in general a smaller form. On account of the small amount 

 of material available, it has been thought inadvisable to give a 

 specific denomination at the present time. 



Gotypes.—V.^.'^M. nos. 497872 and 497873. 



Occurrence. — Rare in the Tantoyuca formation, Jackson Eocene. 

 The above description is based on specimens obtained east of Tempoal, 

 Veracruz ; collection of Dr. P. von Schumacher no. 1624. 



OPERCULINOIDES species B 



Plate 12, Figure 3 ; Plate 20, Figure 7 ; Plate 21, Figure 5 



Test small, compressed lenticular, completely involute, surface 

 smooth, without ornamentation, septa showing as lines of clear shell 

 material. A number of small, regularly spaced tubercles occur be- 

 tween the septa, in a line parallel to and near the periphery (see 



