INSTITUTE OF SCIENCE, PHILADELPHIA. 425 



Subfamily EMARGINULIN.4i. 

 Genus FISSURIDEA Swainson. 



Fissuridea Swainson, Malac, p. 356, 1840; Pilsbry, in Nautilus, v. p. 104, 1892. 

 Glyphis Carpenter, 1S56 ; not of Agassiz, 1843. 



In the Eocene this group is represented in the Claibornian by the hand- 

 some large F. tenebrosa Conrad, of which F. claiborneiisis Lea is a synonym ; 

 from Newton and VVahtubbee, Miss., Meyer and Aldrich have described F. 

 alitor. From the Vicksburgian F. mississippiensis is described by Conrad, 

 and the same species occurs in the Older Miocene rocks of Northwestern 

 Florida, in the form of casts, if correctly identified. 



The approximation of the different groups of higher value than species, 

 as we recede in time, is well illustrated by F. tenebrosa, where the cross bar 

 behind the apical foramen has so deep a dint behind it that it seems difficult 

 to say whether the species shall be referred to Fissuridea or Pjinctiirella. 



In the Older Miocene of New Jersey we have F. Griscomi Conrad ; F. 

 chipolana n. s., and F. nucula n. s., appear in Floridian rocks of the same age- 

 In the Chesapeake or Newer Miocene occurs F. redimicida Say, normally 

 high, conical, with a rather small, very cylindrical foramen. A very young 

 shell, probably of this species, forms the type of Cemoria oblonga H> C. Lea. 

 The typical redimicida has the sculpture even and closely approximate, but 

 from this, by the greater prominence of a few of the radial riblets, we pass to 

 the variety alticosta Conrad (alticostata Meek). F. catilliformis Rogers (1839)1 

 is normally lower, and more compressed laterally and elongated, usually with 

 a very- large, rather oval, foramen ; and close, compact, flattened sculpture. 

 F. marylandica Conrad (1841) and F. nassula Conrad (1845) are synonyms. 

 I have examined the types of both. A recent species F. Tanneri Verrill, has, 

 much the sculpture of F. catilliforinis, but has a small, cylindrical foramen some- 

 what like redimicida, but smaller. F. redimicida and catilliformis are very 

 closely related, and perhaps may prove to be local races of the same species. I 

 find F. redimicida and alticosta most common in Virginia and F. catilliformis 

 and nassula in Maryland. The latter extends to Murfreesboro', North Carolina, 

 and the vicinity of Darlington, Peedee River and Goose Creek, South Carolina, 

 and the upper bed at Alum Bluff in Florida. It is figured under the name of 

 redimicula by Tuomey and Holmes. The Old Miocene F. Griscomi is a 

 smaller, somewhat lower and more elongate species with a long-oval foramen, 

 but also very closely related to the others. 



Fissuridea carolinensis Conrad. 



Plate 21, figure 7. 



Fissurella carolinensis Conrad, Geol. N. Car., App., p. 22, pi. 4. fig. i, 1875. ) 



Fissuridea carolinensis Pilsbry, Nautilus, v. p. 106, 1892. 



Newer Miocene of the Cape Fear River, North Carolina, Johnson; 



