A NEW NEMATODE, SINCOSTA ABERRANS, NEW GENUS, 

 AND NEW SPECIES FR0:M A R0DP:NT 



By Glen WOOD C, Roe 



Of the Zooloijical DivWion, Bureau of Animal IiuJustry, United States Depart- 

 ment of Agneulture. 



The specimens described here are from a collection made by Dr. 

 H. W. Graybill at Monmouth Junction, N. J., from the small intes- 

 tine of a " wild mouse." ^ This nematode belongs to the family 

 Trichostrongylidae Leiper, 1912, and the subfamily Heligmosominae 

 Travassos, 1914. This species appears to belong to a neAv genus, for 

 which the name Sincosta is proposed. 



I wish to thank Dr. M. C. Hall, chief of the zoological division, 

 and Dr. E. W. Price, of the same division, for suggestions in con- 

 nection with the study of this worm. 



SINCOSTA, new genus 



Generic diag^nosh. — Heligmosominae: Worms delicate and whitish 

 in color ^rhen preserved. Cephalic cuticle inflated, usually asym- 

 metrically (fig, 1). Male bursa well developed, definitely asymmetri- 

 cal and indistinctly trilobed. The bursal raj^s (fig. 2) are asymmet- 

 rical to some extent and in the type and only known species are 

 as follows: The ventro-ventral and the latero-ventral rays on both 

 sides of the bursa are united in about their proximal third, with 

 the latero-ventral ray on the right side considerably thicker and 

 somewhat longer than the other rays. The externo-lateral, medio- 

 lateral, and postero-lateral rays on both sides of the bursa are united 

 in at least their proximal third, are divergent distally and are of 

 about equal size. Each externo-dorsal arises from a thickened heavy 

 base, and usually one base exhibits a Icnob on its median aspect and 

 the other base a corresponding depression opposite it. Dorsal ray 

 absent. This lack of a dorsal ray is the most striking of the generic 



1 The ori^nal source of the material was designated by Mr. H. W. Graybill in 1923 as a 

 " wild mouse " and no further information could be obtained from him as to the identity 

 of the host. 



No. 2788.— Proceedings U. S. National Museum, Vol. 75, Art. 17. 



332j4— 29 1 



