224 [April 



Description of some new genera and species of North American LIMNOBINA. 



BY BARON R. OSTEN SACKEN. 



PART I. 

 (Communicated March 13, 1865.) 



Since my previous publications on North American Limnobina (in 

 the Proc. Acad. Nat. Sc. Phi/., 1859 and 1861) I have been gradu- 

 ally collecting materials for a new and more complete work on the same 

 subject, which, together with the work of Mr. Loew on Ttpulina, was 

 intended to form the third volume of the Monographs on the North 

 American Diptera. This volume would have thus contained a com- 

 plete monograph of the family of Tipuli<hr. My manuscript was already 

 sent to the Smithsonian Institution in Washington, to be accepted for 

 publication, when it was lost during the late fire in the building of that 

 Institution. Unfortunately, I had retained no copy. Anticipating a 

 voyage to Europe early in the spring. I had hoped to see the manuscript 

 go through the press before that time, and hurrying to get it ready, did 

 not stop to have it copied, which would have involved a loss of several 

 weeks. Except the fragments which I publish here, I have absolutely 

 nothing in hand now, and the whole work will have to be done over 

 again, including many observations on the structure of the genital 

 organs, of the antennae and palpi, etc., made on living specimens and 

 written down on scraps of paper, which I, for the most part, (very im- 

 prudently) destroyed, as soon as the contents had been incorporated in 

 the text. 



So much as an explanation of the delay which will probably occur 

 before I will be able to replace the lost manuscript. In the meantime, 

 I intend to publish here a small portion of it, which I had kept back 

 for the sake of some additions, and which thus escaped destruction. I 

 will also add notices on the new genera of Limnobina, discovered in 

 this couutry since my last publications, and short descriptions of the 

 most remarkable of the new species. 



The subdivisions, provisionally introduced by me in my first paper on 

 Limnobina (Proc. Acad. N. S. Phil. 1859), were retained in the new 

 monograph, as the following table shows: — 



