1854.] 29 



caudal than to the tip of snout. Ventrals, as usual, in advance of the dorsal, and 

 anal behind the latter. Greatest length of caudal constituting nearly the seventh 

 of the entire length. The scales assume a greater uniformity according to the 

 resions than in the other species hitherto described. 



D I. 8+1. A I. 9. C 5. I. 9. 8. I. 4. V 9. P. 17. 



Color in alcohol ; dark reddish brown above, and on the side ; dull yellow 

 beneath. 



Rio Santa Cruz, tributary of the Gila John H. Clark. 



19. Gila pulchella, B. and G. Allied to the preceding species, from which it 

 can be distinguished by the more slender body and head. The head is shorter. 

 The mouth smaller. The greatest depth is contained about five times in the en- 

 tire length ; in Gila gibbosa but four times. Diameter of the eye entering five 

 times and a half in the length of the side of head. Length -of caudal forming 

 about the sixth of the entire length. Two rudiments of spines at the anterior 

 margin of dorsal, instead of one. 



D IT. 9. A I. 9. C 4. I. 9. 8. 1. 3. V 9. P 17. 



Color, greyish brown above and on the side : dingy yellow beneath. 



Rio Mimbres, tributary of the Gila. John H. Clark. 



'Rectification of the generic names of Tertiary Fossil Shells. 



By T. A. Conrad. 



Since the publication of several papers on Tertiary fossils, I have, with the 

 aid of more numerous works of reference, been enabled to rectify the nomen- 

 clature of some genera, selecting the earliest authority, whether the author had 

 published a diagnosis or only indicated a genus by refeience to atypical species. 



GLYCIMERIS, Lam. 



G. americana, Con. ; G. reflexa, Say ; G. elongata, Co??., 1535 ; G. goldfussii, 

 Wagner ; G. elongata, Con. ; G. porrecta, Con. ; (Panop^ea.) 



Gloss us, Poli. 



G. rusticus, Sowerby ; G. Markoei, Con. (Isocardia.) 



Syndosmya, Recluz. 



S. aequata, Con. ; S. constricta, Con. ; S. linosa, Con. ; S. mississippiensis,. 

 Con.; S. nuculoides Con.; S. protexta, Con.; S. subobliqua, Con.; S. subre- 

 flexa, Co??. (Aiuphidesma.) 



Mytiltjs, Lin. 

 M. incurvus, Con. (Myoconcha incurva, Con.) 



Navicula, Blai?i. 

 N. Marylandica, Con, ; N. cuculloides, Con. ; N. lima, Con. ; N. mississippi- 

 ensis, Co?i. ; N. protracta, Con. (Byssoarca.) 



Leda, Sch?i??i. Nucula, Lam. 



L. acuta, Con. ; L. sequalis, Co??. ; L. bella, Con. ; L. calcarensis, Con. ; L. 

 carolinensis, Co?i. ; L. ccslata, Co?i. ; L. concentrica, Say; L. cultelliformis, 

 Rodgers ; L. laevis, Say ; L. liciata, Con.; L. limaluta, Say ; L. mucronata, 

 Con. ; L. opulenta, Co??. ; L. parva, Rodgers ; L. serica, Co??. ; L. subtrigona, 

 Con. ; L. tellinula, Co?i. ; (Nucula.) 



Mercenaeia, Schttm. Venus, Li?i. 



M. capax, Co??. ; M. Ducatellii, Co??. ; M. Mortoni, Co?i. ; M. permagna, Co??.; 

 M. Rileyi, Co??. ; M. staminea, Con. ; M. tetrica, Co??. ; M. tridacnoides. Lam. 

 (Venus.) 



Meretrix, Lam. Cytherea, Lam, 



M. a?quorea, Co?i. ; M. albaria, Say ; M. astartaeformis, Co??. ; M. carolinen- 



