NATURAL SCIENCES OP PHILADELPHIA* 155 



rmgulata ; valvulis subcrassis ; natibus subelevatis, ad apices minute undulatis 

 epidermide luteola, striata ; dentibus cardinalibus permaguis, subcompressis. 

 elevatis, obliquis crenulatisque ; lateralibus longis rectisque ; margarita argentea 

 et iridescente. 

 Ilab. Rutcrsville, Texas. Prof. C. G. Forshey. 



Unio Houstonensis. -Testa lavi, subrotunda, subinflata, ffiquilaterali, ad 

 latere paulisper planulata ; valvulis subcrassis, antice crassioribus ; natibus 

 elevatis, ad apices paulisper undulatis ; epidermide laevi, virido-lutea, vel era- 

 diata vel obsolete radiata,; deutibus cardinalibus magnis, erectis, crenulatis 

 lateralibus curtis subrectisque ; margarita argentea et iridescente. 



Ilab. Houston, Texas. F. Moore, M. D. 



Unio Rctersvillensis. Testa lsevi, transverse elliptica, subinflata, valde 

 inaequilaterali, postice obtuse angulata ; valvulis subtenuibus, antice paulisper 

 crassioribus ; natibus prominulis, ad apices regulariter et elegantissime undu- 

 latis ; epidermide vel fusca vel luteo-fusca et valde radiata; dentibus cardina- 

 libus parvis, compressis, acuminatis, crenulatis, in utroque valvulo duplicibus : 

 lateralibus longis, lamellatis subcurvisque ; margarita. ceruleo-alba et valde 

 iridescente. 



Ilab. Rutersville, Fayette Co., Texas. Prof. C. G. Forshey. 



Unio Forsheyi. Testa valde et minute tuberculatum, subquadrangulari, com- 

 pressa, subequilaterali, postice subbiangulata; valvulis subcrassis, antice cras- 

 sioribus ; natibus subelevatis, ad apices acuminatis et elegantissime perundu- 

 latis ; epidermide virido-lutea, substriata, obsolete radiata, submicante ; den* 

 tibus cardinalibus subgrandibus, erectis, crenulatis, in utroque valvulo dupli- 

 cibus, lateralibus rectis brevibusque ; margarita argentea et paulisper iridescente 



Hab. Fayette Co., Texas. Prof. C. G. Forshey. 



Description of a Third Genus of HEMIRHAMPHIN.2E, 



BY THEO. GILL. 



After the transmission to the Academy of Natural Sciences of the paper de- 

 scriptive of the genus Ilgporhamphus, Mr. James C. Brevoort placed in my hands 

 a species closely resembling those fishes which have been described as Hemi- 

 rhamphus lo7igirostris and //. macrorht/nchus. Mr. Brevoort at the same time 

 called my attention to the peculiar dentition of the species, there being evidently 

 tricuspidate teeth in the lower jaw, while those in the upper were simply coni- 

 cal. On an examination of the descriptions of the above mentioned species, as 

 given in the " Histoire Naturelle des Poissons," it is to be remarked that no al- 

 lusion is made to the shape of the teeth, but that they are in each described as 

 being very fine, immediately after the statement of the size of the upper jaw. 

 It is then to be presumed that M. Valenciennes only noticed the conical teeth, 

 for one of the characters that he has given of the genus is founded on the 

 presence of granular or conical ones. Could Valenciennes have overlooked the 

 teeth of the lower jaw, and only examined those of the upper? It appears to 

 me possible that he did, for it is scarcely to be believed that a fish so closely 

 resembling Hemirhamphus longirostris as the present species, could differ from 

 it in such important parts. I nevertheless offer this opinion with diffidence. 

 As Valenciennes has remarked, the teeth are very small, and as their forms can 

 only be discerned through a magnifier, they might have been easily overlooked, 

 unless the attention of the observer was particularly attracted to them. The 

 peculiarity of the different structure of the teeth in each jaw would scarcely have 

 been suspected by the naturalist as occurring in this tribe. If this supposition 

 is correct, as to the Hemirhamphus longirostris and H. macrorhynchus, those 

 species should be withdrawn from the genus Hemirhamphus and placed in an 

 allied one. Valenciennes would probably have himself done this, if he had 



1859.] 



