172 [September, 



abruptly turned up ; exterior surface with vertical impressed lines correspond- 

 ing with the ridges on the lip ; cirri or ramifications of the mantle impressed, 

 dichotomously branching ; cells towards the circumference compressed length- 

 wise. 



The numerous radiating ridges on the lip are characteristic of this species. 



Locality , Lowndes county, Alabama. 



3. R. Aimesii. Shell, lower valve large, conical, very thick ; lip slightly con- 

 vex, with narrow, radiating depressions towards the inner circumference, outer 

 edge slightly plaited, with obsolete concentric undulating lines ; outer surface 

 striate. 



Inscribed to Dr. Aimes, of Montgomery, to whose kindness I owe this fine 

 fossil. 



Locality , Alabama. 



4. R. undulata. Shell, lower valve thick; lip bent slightly upwards, with dis- 

 tant, obtuse radiating ridges, or undulations, and obsolete radiating lines ; cirri 

 of the mantle well defined. 



Locality, Marengo county, Alabama. 



Ichthiosarcolites, Desmarest. 

 Caprinella, d'Orb. 



1. /. quadrat) gularis. Shell quadrangular, curved, irregular ; septa somewhat 

 regular, abruptly bent downwards, and approximating in the channel on the 

 inner surface of the shell; aperture terminating obliquely and rather abruptly. 



Locality, Noxubie county, Mississippi. Mr. Richardson. 



2. I. loricatis. Shell, aperture somewhat oval, irregular, obtusely rounded at 

 the base, giving the cast an imbricated appearance. 



Locality, Noxubie county, Mississippi. Mr. Richardson. 



3. I. eornutis. Shell, aperture regularly curved, flattened on one side, septa 

 abruptly bent downwards, and towards the concave side. 



Distinguished from the preceding by the more distant and regular septa, and 

 in the greater regularity of the curvature of the shell. 



Locality, Noxubie county, Mississippi. Mr. Richardson. 



I have thought proper to restore Desmarest's uncouth name, rather than 

 violate the rule of priority. 



Description of a fossil apparently indicating an extinct species of the 



Camel tribe. 



By Joseph Leidv, M.D. 



Mr. Henry Pratten, of New Harmony, Indiana, has sent for my inspection, 

 and as a donation to our Academy, an interesting fossil, which be discovered in 

 the gravel drift of Kansas territory. 



The specimen consists of the left intermaxillary bone, containing the fang of 

 a tooth, and a small portion of the corresponding maxillary bone. 



The fang of the tooth is the portion of a transformed incisor or functional 

 canine, like that in the Camel and Lama. The crown of the tooth was directed 

 more outwardly than in either of the latter; but it had the same form, being 

 laterally compressed, obtuse anteriorly and acute posteriorly. At the point of 

 emergence from its alveolus the crown measured 61 lines antero-posteriorly and 

 3j lines transversely. Its enamel is thin, and appears to have been smooth. 

 The fang is laterally compressed, conical, and measures an inch and a half in 

 length ; and it is strongly curved backward and downward, and is almost paral- 

 lel with the palatal margin, so that its extremity is only seven lines above the 

 latter. 



The intermaxillary bone is relatively larger and more robust than in the 

 Camel or Lama, and it is broader and more convex above. Its nasal border is 



