INSTITUTE OF SCIENCE, PHILADELPHIA. 36 1 



names had been misapplied to the two species in the old Smithsonian collec- 

 tion, as was proved by the original diagnoses. In the recent fauna two types 

 of this family are represented, the present species and A'. [Tiiguriuni) caribbcea 

 Petit. The typical form is more elevated, has only a slight chink or even no 

 umbilical perforation (individuals vary in this respect at different ages), and the 

 periphery is not produced into a lamina. In Tugiirmm the periphery is thin 

 and produced far beyond the normal whorl, and there is a funicular umbilicus. 

 There are also anatomical differences. In the Eocene we have the present 

 species and also X. Intmilis Conrad, which is depressed and has a moderate 

 umbilicus, but the periphery not lamellar, and the upper surface well covered 

 with attached bodies. It is found in the " white limestone " of Claiborne 

 Bluff (Jacksonian), at Jackson and Vicksburg, Miss., and in the limestone of 

 Richards' quarry at Ocala, Florida, belonging to the final or nummulitic 

 phase of the Vicksburg. 



It is followed in the Older Miocene of the Chipola beds by an analogous 

 form, X. textilina Dall, which differs in having the granulation of the surface 

 coarser and stronger, being marked even on the upper surface, and in having 

 the base, especially round the umbilicus (which is small and sometimes nearly 

 closed), distinctly spirally grooved. This shell reaches 55 mm. in diameter 

 (exclusive of its load, which is a large one), has eight or nine whorls, and an 

 elevation of 35 mm. The basal grooves are shallow and narrower than their 

 interspaces, which have the effect of half a dozen flattish spiral ribs. The 

 .umbilicus is larger than in X. concliyliophora, but not so large as in Tiigurmm. 

 The basal margin is little excavated, and not at all produced. 



Xenophora extensa Sby. was identified from the Shark River, N. J., 

 Eocene by Conrad, but the species found there is not likely to be the British 

 shell, but is more probably X. humilis. 



Xenophora lapiferens Whitfield is an interesting new species from the 

 New Jersey Eocene marls. Its load is composed of single pebbles, which are 

 attached on the middle of the whorl instead of near the edge (a peculiarity I 

 have not noticed in any other species), and not very close together; thus the 

 regularity of the suture is little interfered with, and with the exception of the 

 pits of attachment the spire forms a nearly smooth cone more than twice as 

 wide as it is high. The umbilicus is closed and the base slightly convex or 

 flattish, not excavated near the periphery. 



From the Eocene of Carson's Creek, Wayne County, Miss., five miles 

 south of Shubuta, we have an mteresting species of the other subgenus, X. 

 {Tiigurium) conic a Dall. This has the periphery extended in scalloped points 

 each of which bears a very small extraneous piece of shell, or none; the spire 

 is flatly conical, with a subacute apex and eight whorls, the suture closely 

 appressed; the surface is marked by lines of growth and a few obsolete spiral 

 striae near the periphery; the base is similarly sculptured, almost smooth, 

 excavated near the periphery, with a funicular umbilicus in which the lines of 



