76 NATICA. 



4. Ampullina. a. Jiuctuata. 



5. KuMA. Small spire, large and wide mouth. Operc. 

 horny, narrow. Ex. R. mamillaris and Sebce. 



6. Mamma. No characters applicable to all the species 

 enumerated. Ex. 31. Draparnaiuli and Caribcea. 



Species. 



Operculum thin, horny. 



1. OLLA, f. 1, Marcel de Serves. — Grlobosa, solida, superne 

 glauco-fusca, infra alba ; spira brevi, anfractibus subrotundis 

 umbilico lato, profundo, callo columellari simplici fulvo, 

 dimidiatim umbilicum tegenti ; apertura mediocri, labio 

 externo obtuse rotundo. — The most globose shell of the group 

 to which it belongs. The callus is swelled on the body- 

 whorl, and projects in a round form so as to cover about half 

 the umbilicus. It is simple. The N. glaucina of Lamarck 

 is this shell, but that of Linnaeus belongs to another set. 



2. CAMPECHENSis, f. 7, Recluz. — Prsecedenti similis, sed 

 depressa, lateraliter expansa, callo columellari rotundo, um- 

 bilicum fere tegenti. — This may be considered the typical 

 form of the group to which it belongs. It is much depressed, 

 and the umbilicus is nearly covered in by the tumid and 

 expanded callus. 



3. Recltjziana, f. 6, Deshayes. — Conica ; spira exserta, aliter 

 N. Gampechensi affinis, callo magis linguseformi ; anfractibus 

 prope suturam fusco fasciatis.— -With the essential characters 

 of the group, this species has a conically elevated form, 

 produced by lateral compression. 



4. Baconi, f. 2, Reeve. — Quam N. olla magis obliqua, an- 

 fractibus superne depressis, callo umbilicali simplici sed 

 planulatim concave. — Much more oblique and depressed than 

 the preceding. It has the umbilical callus undivided, but 

 flattened and depressed. 



5. glauca, f. 5, Humboldt. — Gampechensi similis, sed 

 oblique valide depressa, apertura lateraliter expansa callo 

 umbilicali parvo, producto, linguaeformi, columella obliqua. — 

 Very obliquely depressed, with a small tongue-shaped, dark 

 callus projected partly over the umbilicus, and a very oblique, 

 thin columella. 



