228 TRANSACTIONS OF THE WAGNER FREE 



A fine series was obtained by Mr. Willcox of tliis puzzling form. It is 

 smaller than dubia or nmtabilis, and is, perhaps, the earliest species of this line 

 of development which we call Aitrinia. It has a small, bulbous nucleus like 

 that of dubia, and five subsequent whorls, while obtusa of about the same size 

 has only four whorls. There are two very stout, thick but not clear-cut 

 plaits, which are not so oblique as in most of the species, the sutural margin 

 of the whorl is constricted, and the transverse riblets on the early whorls in 

 most specimens are rather conspicuous. 



There seems little reason to doubt that this is distinct, though it verges 

 pretty close to some varieties of the inutabilis-obtusa form. I have already 

 pointed out that Conrad's first specific name must be rejected as in direct con- 

 flict with fact, and that it would be as well to adopt his MS. name of virginimia 

 applied to the same species in the collection of the Academy of Natural 

 Sciences, Philadelphia. 



Subgenus Caricella Conrad. 

 Scaphella (Caricella) podagrina Dall. 

 Plate 20, figure 9. 

 C. podagrina Dall, part i. p. 86, 1890. 



One of the typical specimens is now figured to illustrate the species. 



Family MITRID^ (sup[)lementary). 

 Genus PERPLIOABIA Dall. 

 Perplicaria perplexa Dall. 

 Plate 3, figure i ; plate 13, figure 4. 

 Perplicaria perplexa Dall, part i. pp. 90, 181, 1890. 

 Pliocene of the Caloosahatchie and Shell Creek, Dall and Willcox. 

 Much to my satisfaction, among the shells presented by Mr. Willcox to 

 the National Museum in 1891, collected by him at Shell Creek, Florida, a 

 mature specimen of this singular form turned up. This is a good deal smaller 

 than the CalooSahatchie specimen would have been if perfect, but presents 

 the characters sufficiently, and has been figured. It measures 17.5 mm. long, 

 the aperture 9.0 mm. and the maximum diameter is 6.0 mm. The discovery 

 of the entire shell, unfortunately, does not clear up its systematic relations. 

 It proves to have two plaits, extremely oblique, a lirate, patulous outer lip, a 

 canal so short, wide and straight as to be hardly recognizable as such. From 

 the mitras of the section Mauritia it differs by its paucity of plaits, their ob- 

 liquity, and the absence of a recurved canal. The latter is also present in 

 Dibapliiis edentidus. Perhaps this species may be regarded as most nearly 

 allied to Mitra. It has not, so far as known, any recent analogue. 



Genus Mitra Lamarck. 

 Mitra carolinensis Conrad. 

 Specimens of M. carolinejisis obtained by Mr. Willcox in North Caro- 



