NATURAL SCIENCES OF PHILADELPHIA. 197 



rior borders are midway between the snout and opercular margin ; the distance 

 from each other is as seven to three, but the interorbital space is only as five 

 and a half to three. 



The roof of the mouth is studded with papillae, especially in a transverse 

 line on the palate. 



The lips are thick and minutely papillated. 



The maxillary barbels are attenuated at their ends, and extend to or beyond 

 the caudal base. 



The teeth are straight and compressed, with parallel sides, and imbedded in 

 the gums ; the distance between each is equal to its width. There are more 

 than forty in the upper, and more than fifty in the lower jaw. Behind the 

 teeth there is a papillated ridge, but no teeth. 



There are eight branchiostegal rays. 



A distinct pectoral pore is present. 



The dorsal commences behind the second fourth of the length of the fish, and 

 its anterior ray is longest, and almost equals the height of the body. 



The adipose fin is very long and abruptly truncated posteriorly ; it is dis- 

 tinctly striated, so as to present a finely rayed appearance. 



The caudal fin is deeply lunate ; its central rays form an eleventh of the 

 extreme length, and its longest are equal to a fifth. 



The pectorals are pointed, and equal a fifth of the length. 



The ventrals are shorter than the pectorals, and the second ray is longest. 



The following formula indicates the number and character of the rays : 

 1 1 



D 1, 5 ; A 4, 8 - ; C 19, I, 7, 8, I, 13 ; P I, 12 ; V I, 15. 



1 1 



The color is silvery beneath, and above merges into a light purplish hue. 

 Along the side there are a number of distinct, nearly round dusky spots. The 

 fins are pearly, opaque at the bases. 



The specimen from which this description has been taken, was presented 

 by Mr. A. Edwards to the Lyceum of Natural History, of New York. It was 

 obtained from the Amazon River, with Cetopsis candiru Ag., Enctenogoblns 

 bodius Gill, Sternojjygus macrurus M. and T., and other species. 



New genera and species of North American TIPULID2E with short palpi, with 

 an attempt at a new classification of the tribe. 



BY BARON R. VON OSTEN SACKEN. 



Little attention has been paid by former authors to the North American 

 species of the genera Limnobia Meig., and E ri op te ra Meig., and the 

 number of those already described is not at all in proportion to the great num- 

 ber of species of some other genera, which have been made known, (as, for. 

 instance, Tabanus, Anthrax, and the family of Asilidae.) 



In my Catalogue of the described Diptera of North America, published in 

 1858 by the Smithsonian Institution, not more than 23 species, coming within 

 the scope of the present publication, are enumerated.* The considerable 

 number of new species of this family contained in my collection of North 

 American Diptera, induced me to undertake their publication. 



It was only natural to expect that among so many new species, some new 

 genera would occur. Whosoever has paid any attention to the classification 

 of the Tipulidce with short palpi, knows how very imperfect this classification 

 is, and how the principal genera are established on the habitual and artificial 

 characters. It became necessary, therefore, before proposing new genera to 

 revise the old ones, and to establish them on better characters. I have attempted 

 this, but in judging what I have done, it should be borne in mind, that this 

 1859.] 



