AMERICAN DIPTERA. 247 



THE DIPTKROLTS FAMILY 3fEMKSTRI MD^. 



BY T. D. A. COCKERELh. 

 (Plate XVI). 

 My attention was first called to the Neniestrinida' by the dis- 

 covery of a beautifully preserved specimen {Hirmoneura vielanderi, 

 fig. 4) in the miocene shales of Florissant, Colorado. A second 

 fossil species of the same genus was found among some Florissant 

 material collected long ago, and now in the Museum of Yale Uni- 

 versity. Professor A. L. Melander, with great generosity, loaned 

 me all his material of this family, representing three species of 

 Nemedrina from Turkestan, two of Hhynehocephalus, and a beauti- 

 ful Hirmoneura from Texas. The last was recognized by him as 

 new, and it is with his kind permission that I describe it. Professor 

 A. P. Morse very kindly sent me particulars about Scudder's tyj)e 

 of Palembolus ; and to Dr. L. O. Howard and his associates I am 

 indebted for copies of several descriptions, the loan of specimens of 

 Bhynchocephulus and the excellent reproductions of the figures of 

 R. sackeni and Hirmoneura brevirostris ( figs. 2 and 3). The photo- 

 graph of the type of IT. melander'i was made at the American 

 Museum of Natural History, and is here published with the kind 

 permission of Dr. Bumpus. 



The Nemestrinidse constitute a very ancient family of brachy- 

 cerous Diptera, a species {Prohirmoneiira jurassiea Handlirsch) 

 having been discovered in the Jurassic rocks of Bavaria. Today, 

 they are much reduced in numbers, and in North America are so 

 rare that there are many Dipterologists who have never taken a 

 specimen. They were probably more numerous in miocene times, 

 since three have been described from Florissant — a number alto- 

 gether exceeding what might be expected in any similar deposit 

 made in America at the present time. 



In their venation they are singularly variable (see fig. 1, showing 

 variation in R. sackeni), characters which would be of generic value 

 in some other families, proving inconstant here within specific limits. 

 - Dr. Williston, in a recent conversation, remarked to me that in In's 

 experience it seemed that waning types often showed such varia- 

 bility ; whether the morphological break-up is the result or the 

 cause of the failure to persist is an open question. 



TEAMS. AM. KNT. KOC. XXXIV. (31 ■) AUGUST, 1908. 



