NATURAL SCIENCES OF PHILADELPHIA. 231 



b. 0. postorbitale produced over the superciliary 



region Achrochordidse.* 



bb. Postorbitale forming the hinder border of the orbit only. The 



families of this group have not yet been denned. 



V. 0. maxillare horizontal, thickened, and not reaching 



premaxillare anteriorly, in contact with prefront- 

 ale, bearing a perforate and usually grooved tooth Proteroglypha. 

 *. Caudal hypapophyses bifid. Neural spines and 

 pleurapophyses short. 



Postorbitals wanting ; no splenio-mental groove E 1 a p i d ae. 



Postorbitals present N a j i d se. 



/?. Caudal hypapophyses simple. 

 Neural spines and pleurapophyses elongate. A post- 

 frontal bone Hy d r o p h i dse. 



VI. 0. maxillare vertical, attached to prefontale by a gin- 



glymus, and to the ectopterygoid without imbri- 

 cation. Fang very seldom grooved Solenoglypha. 



Embracing the families Atractaspidse, C a u s i d se, Viperidae and 

 Crotalidse. For characters vid. Pr. A. N. Sci., 1859, 334. 



On a Blind SILTIRID, from Pennsylvania. 



BY E. D. COPE. 



Animals deprived of the sense of sight are generally known inhabitants of 

 subterranean areas of earth or water, although representing by their general 

 structure, zoological groups most diverse. Among fish, two blind species of 

 the Cod family are found in the caves of Cuba. The blind fish of the Mam- 

 moth Cave, with its sightless relative, the Typhlichthys, belong to a family 

 represented by an eyed genus in the ditches of Carolina. Among the Catfish 

 or Siluridae there are sundry genera of a variety of form, in which the eyes 

 are wanting or concealed by the skin. These are mostly South American or 

 East Indian species, those of the latter country, of the Akysis type, approach 

 nearest to our eyed Catfish of North America, according to the system of 

 Bleeker. For a knowledge of the first genus of blind Silurid from our country, 

 I am indebted to my friend Jacob Stauffer, Secretary of the Linnsean Society 

 of Lancaster, an ardent explorer of the Zoology and Botany of Southern Penn- 

 sylvania, and who has furnished me with many valuable notes and specimens. 

 This fish, of which specimens have been taken in the Conestoga creek, a tribu- 

 tary of the Susquehannah, is simply a blind representative of the ordinary type 

 of Silurids, characteristic of North America, and is not to be arranged with the 

 exotic groups. It, therefore, enters the group Ictnluri, of Gill, with our genera 

 Ameiirus, Hopladelus, Noturus and Ictalwrus, possessing especially the charac- 

 ters of the first. The genus may be called Gronins, and be explained by the 

 following diagnosis : Head broad, depressed. Supraoccipital bone posteriorly 

 free. Branchiostegal membrane with ten rays. Anterior dorsal spine stout, 

 posterior fin separated from caudal. Ventrals with eight rays. Eyes rudi- 

 mental, covered by the corium. Natatory bladder present. 



The species has the head broader posteriorly, and the anal fin shorter than 

 in the allied species of Ameiirus. It may be called G. n igr i 1 a b ris. The 

 muzzle is flat and the jaws equal ; the width across the occipital region is 

 equal to the length from the end of the muzzle to the apex of the occipital 

 crest ; width below equal from the axilla of the pectoral to the base of the 

 ventral fin. From end of muzzle to dorsal spine equal from latter to middle 

 of adipose. Length of head four and one-fifth times in total length. Max- 



1864.] 



* Vid. Pr. A. N. S., 18C0, 75. 



